diff --git a/README.md b/README.md
index 6686a2b..5bf9ed1 100644
--- a/README.md
+++ b/README.md
@@ -64,9 +64,10 @@ use Box\Spout\Common\Type;
 $reader = ReaderFactory::create(Type::CSV);
 $reader->open($filePath);
 
-while ($reader->hasNextRow()) {
-    $row = $reader->nextRow();
-    // do stuff
+foreach ($reader->getSheetIterator() as $sheet) {
+    foreach ($reader->getRowIterator() as $row) {
+        // do stuff
+    }
 }
 
 $reader->close();
@@ -81,11 +82,8 @@ use Box\Spout\Common\Type;
 $reader = ReaderFactory::create(Type::XLSX);
 $reader->open($filePath);
 
-while ($reader->hasNextSheet()) {
-    $reader->nextSheet();
-
-    while ($reader->hasNextRow()) {
-        $row = $reader->nextRow();
+foreach ($reader->getSheetIterator() as $sheet) {
+    foreach ($reader->getRowIterator() as $row) {
         // do stuff
     }
 }
@@ -202,8 +200,7 @@ $sheets = $writer->getSheets();
 If you rely on the sheet's name in your application, you can access it and customize it this way:
 ```php
 // Accessing the sheet name when reading
-while ($reader->hasNextSheet()) {
-    $sheet = $reader->nextSheet();
+foreach ($reader->getSheetIterator() as $sheet) {
     $sheetName = $sheet->getName();
 }
 
@@ -253,7 +250,7 @@ For information, the performance tests take about one hour to run (processing 2
 
 When writing data, Spout is streaming the data to files, one or few lines at a time. That means that it only keeps in memory the few rows that it needs to write. Once written, the memory is freed.
 
-Same goes with reading. Only one row at a time is stored in memory. A special technique is used to handle shared strings in XLSX, storing them into several small temporary files that allows fast access.
+Same goes with reading. Only one row at a time is stored in memory. A special technique is used to handle shared strings in XLSX, storing them - if needed - into several small temporary files that allows fast access.
 
 #### How long does it take to generate a file with X rows?
 
diff --git a/phpunit.xml b/phpunit.xml
index fc6d657..06ddf63 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -5,7 +5,6 @@
         colors="true"
         convertErrorsToExceptions="false"
         convertWarningsToExceptions="false"
-        strict="false"
         verbose="false">
 
     <testsuites>
diff --git a/src/Spout/Common/Helper/FileSystemHelper.php b/src/Spout/Common/Helper/FileSystemHelper.php
index d7ca64f..6186822 100644
--- a/src/Spout/Common/Helper/FileSystemHelper.php
+++ b/src/Spout/Common/Helper/FileSystemHelper.php
@@ -63,7 +63,7 @@ class FileSystemHelper
         $filePath = $parentFolderPath . '/' . $fileName;
 
         $wasCreationSuccessful = file_put_contents($filePath, $fileContents);
-        if (!$wasCreationSuccessful) {
+        if ($wasCreationSuccessful === false) {
             throw new IOException('Unable to create file: ' . $filePath);
         }
 
diff --git a/src/Spout/Common/Helper/GlobalFunctionsHelper.php b/src/Spout/Common/Helper/GlobalFunctionsHelper.php
index feeb782..47ed052 100644
--- a/src/Spout/Common/Helper/GlobalFunctionsHelper.php
+++ b/src/Spout/Common/Helper/GlobalFunctionsHelper.php
@@ -160,7 +160,7 @@ class GlobalFunctionsHelper
      * @see file_get_contents()
      *
      * @param string $filePath
-     * @return bool
+     * @return string
      */
     public function file_get_contents($filePath)
     {
diff --git a/src/Spout/Reader/AbstractReader.php b/src/Spout/Reader/AbstractReader.php
index 2e2e2de..bfbedf8 100644
--- a/src/Spout/Reader/AbstractReader.php
+++ b/src/Spout/Reader/AbstractReader.php
@@ -4,7 +4,6 @@ namespace Box\Spout\Reader;
 
 use Box\Spout\Common\Exception\IOException;
 use Box\Spout\Reader\Exception\ReaderNotOpenedException;
-use Box\Spout\Reader\Exception\EndOfFileReachedException;
 
 /**
  * Class AbstractReader
@@ -14,18 +13,9 @@ use Box\Spout\Reader\Exception\EndOfFileReachedException;
  */
 abstract class AbstractReader implements ReaderInterface
 {
-    /** @var int Used to keep track of the row index */
-    protected $currentRowIndex = 0;
-
     /** @var bool Indicates whether the stream is currently open */
     protected $isStreamOpened = false;
 
-    /** @var bool Indicates whether all rows have been read */
-    protected $hasReachedEndOfFile = false;
-
-    /** @var array Buffer used to store the row data, while checking if there are more rows to read */
-    protected $rowDataBuffer = null;
-
     /** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
     protected $globalFunctionsHelper;
 
@@ -38,11 +28,11 @@ abstract class AbstractReader implements ReaderInterface
     abstract protected function openReader($filePath);
 
     /**
-     * Reads and returns next row if available.
+     * Returns an iterator to iterate over sheets.
      *
-     * @return array|null Array that contains the data for the read row or null at the end of the file
+     * @return \Iterator To iterate over sheets
      */
-    abstract protected function read();
+    abstract public function getConcreteSheetIterator();
 
     /**
      * Closes the reader. To be used after reading the file.
@@ -80,9 +70,6 @@ abstract class AbstractReader implements ReaderInterface
             }
         }
 
-        $this->currentRowIndex = 0;
-        $this->hasReachedEndOfFile = false;
-
         try {
             $this->openReader($filePath);
             $this->isStreamOpened = true;
@@ -103,82 +90,18 @@ abstract class AbstractReader implements ReaderInterface
     }
 
     /**
-     * Returns whether all rows have been read (i.e. if we are at the end of the file).
-     * To know if the end of file has been reached, it uses a buffer. If the buffer is
-     * empty (meaning, nothing has been read or previous read line has been consumed), then
-     * it reads the next line, store it in the buffer for the next time or flip a variable if
-     * the end of file has been reached.
+     * Returns an iterator to iterate over sheets.
      *
-     * @return bool Whether all rows have been read (i.e. if we are at the end of the file)
-     * @throws \Box\Spout\Reader\Exception\ReaderNotOpenedException If the stream was not opened first
+     * @return \Iterator To iterate over sheets
+     * @throws \Box\Spout\Reader\Exception\ReaderNotOpenedException If called before opening the reader
      */
-    public function hasNextRow()
+    public function getSheetIterator()
     {
         if (!$this->isStreamOpened) {
-            throw new ReaderNotOpenedException('Stream should be opened first.');
+            throw new ReaderNotOpenedException('Reader should be opened first.');
         }
 
-        if ($this->hasReachedEndOfFile) {
-            return false;
-        }
-
-        // if the buffer contains unprocessed row
-        if (!$this->isRowDataBufferEmpty()) {
-            return true;
-        }
-
-        // otherwise, try to read the next line line, and store it in the buffer
-        $this->rowDataBuffer = $this->read();
-
-        // if the buffer is still empty after reading a row, it means end of file was reached
-        $this->hasReachedEndOfFile = $this->isRowDataBufferEmpty();
-
-        return (!$this->hasReachedEndOfFile);
-    }
-
-    /**
-     * Returns next row if available. The row is either retrieved from the buffer if it is not empty or fetched by
-     * actually reading the file.
-     *
-     * @return array Array that contains the data for the read row
-     * @throws \Box\Spout\Common\Exception\IOException If the stream was not opened first
-     * @throws \Box\Spout\Reader\Exception\EndOfFileReachedException
-     */
-    public function nextRow()
-    {
-        if (!$this->hasNextRow()) {
-            throw new EndOfFileReachedException('End of file was reached. Cannot read more rows.');
-        }
-
-        // Get data from buffer (if the buffer was empty, it was filled by the call to hasNextRow())
-        $rowData = $this->rowDataBuffer;
-
-        // empty buffer to mark the row as consumed
-        $this->emptyRowDataBuffer();
-
-        $this->currentRowIndex++;
-
-        return $rowData;
-    }
-
-    /**
-     * Returns whether the buffer where the row data is stored is empty
-     *
-     * @return bool
-     */
-    protected function isRowDataBufferEmpty()
-    {
-        return ($this->rowDataBuffer === null);
-    }
-
-    /**
-     * Empty the buffer that stores row data
-     *
-     * @return void
-     */
-    protected function emptyRowDataBuffer()
-    {
-        $this->rowDataBuffer = null;
+        return $this->getConcreteSheetIterator();
     }
 
     /**
@@ -190,6 +113,12 @@ abstract class AbstractReader implements ReaderInterface
     {
         if ($this->isStreamOpened) {
             $this->closeReader();
+
+            $sheetIterator = $this->getConcreteSheetIterator();
+            if ($sheetIterator) {
+                $sheetIterator->end();
+            }
+
             $this->isStreamOpened = false;
         }
     }
diff --git a/src/Spout/Reader/CSV.php b/src/Spout/Reader/CSV.php
deleted file mode 100644
index 2da160f..0000000
--- a/src/Spout/Reader/CSV.php
+++ /dev/null
@@ -1,130 +0,0 @@
-<?php
-
-namespace Box\Spout\Reader;
-
-use Box\Spout\Common\Exception\IOException;
-
-/**
- * Class CSV
- * This class provides support to read data from a CSV file.
- *
- * @package Box\Spout\Reader
- */
-class CSV extends AbstractReader
-{
-    const UTF8_BOM = "\xEF\xBB\xBF";
-
-    /** @var resource Pointer to the file to be written */
-    protected $filePointer;
-
-    /** @var string Defines the character used to delimit fields (one character only) */
-    protected $fieldDelimiter = ',';
-
-    /** @var string Defines the character used to enclose fields (one character only) */
-    protected $fieldEnclosure = '"';
-
-    /**
-     * Sets the field delimiter for the CSV
-     *
-     * @param string $fieldDelimiter Character that delimits fields
-     * @return CSV
-     */
-    public function setFieldDelimiter($fieldDelimiter)
-    {
-        $this->fieldDelimiter = $fieldDelimiter;
-        return $this;
-    }
-
-    /**
-     * Sets the field enclosure for the CSV
-     *
-     * @param string $fieldEnclosure Character that enclose fields
-     * @return CSV
-     */
-    public function setFieldEnclosure($fieldEnclosure)
-    {
-        $this->fieldEnclosure = $fieldEnclosure;
-        return $this;
-    }
-
-    /**
-     * Opens the file at the given path to make it ready to be read.
-     * The file must be UTF-8 encoded.
-     * @TODO add encoding detection/conversion
-     *
-     * @param  string $filePath Path of the CSV file to be read
-     * @return void
-     * @throws \Box\Spout\Common\Exception\IOException
-     */
-    protected function openReader($filePath)
-    {
-        $this->filePointer = $this->globalFunctionsHelper->fopen($filePath, 'r');
-        if (!$this->filePointer) {
-            throw new IOException('Could not open file ' . $filePath . ' for reading.');
-        }
-
-        $this->skipUtf8Bom();
-    }
-
-    /**
-     * This skips the UTF-8 BOM if inserted at the beginning of the file
-     * by moving the file pointer after it, so that it is not read.
-     *
-     * @return void
-     */
-    protected function skipUtf8Bom()
-    {
-        $this->globalFunctionsHelper->rewind($this->filePointer);
-
-        $hasUtf8Bom = ($this->globalFunctionsHelper->fgets($this->filePointer, 4) === self::UTF8_BOM);
-
-        if ($hasUtf8Bom) {
-            // we skip the 2 first bytes (so start from the 3rd byte)
-            $this->globalFunctionsHelper->fseek($this->filePointer, 3);
-        } else {
-            // if no BOM, reset the pointer to read from the beginning
-            $this->globalFunctionsHelper->fseek($this->filePointer, 0);
-        }
-    }
-
-    /**
-     * Reads and returns next row if available.
-     * Empty rows are skipped.
-     *
-     * @return array|null Array that contains the data for the read row or null at the end of the file
-     */
-    protected function read()
-    {
-        $lineData = null;
-
-        if ($this->filePointer) {
-            do {
-                $lineData = $this->globalFunctionsHelper->fgetcsv($this->filePointer, 0, $this->fieldDelimiter, $this->fieldEnclosure);
-            } while ($lineData && $this->isEmptyLine($lineData));
-        }
-
-        // When reaching the end of the file, return null instead of false
-        return ($lineData !== false) ? $lineData : null;
-    }
-
-    /**
-     * @param array $lineData Array containing the cells value for the line
-     * @return bool Whether the given line is empty
-     */
-    protected function isEmptyLine($lineData)
-    {
-        return (count($lineData) === 1 && $lineData[0] === null);
-    }
-
-    /**
-     * Closes the reader. To be used after reading the file.
-     *
-     * @return void
-     */
-    protected function closeReader()
-    {
-        if ($this->filePointer) {
-            $this->globalFunctionsHelper->fclose($this->filePointer);
-        }
-    }
-}
diff --git a/src/Spout/Reader/CSV/Reader.php b/src/Spout/Reader/CSV/Reader.php
new file mode 100644
index 0000000..9f9e56f
--- /dev/null
+++ b/src/Spout/Reader/CSV/Reader.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace Box\Spout\Reader\CSV;
+
+use Box\Spout\Reader\AbstractReader;
+use Box\Spout\Common\Exception\IOException;
+
+/**
+ * Class Reader
+ * This class provides support to read data from a CSV file.
+ *
+ * @package Box\Spout\Reader\CSV
+ */
+class Reader extends AbstractReader
+{
+    /** @var resource Pointer to the file to be written */
+    protected $filePointer;
+
+    /** @var SheetIterator To iterator over the CSV unique "sheet" */
+    protected $sheetIterator;
+
+    /** @var string Defines the character used to delimit fields (one character only) */
+    protected $fieldDelimiter = ',';
+
+    /** @var string Defines the character used to enclose fields (one character only) */
+    protected $fieldEnclosure = '"';
+
+    /**
+     * Sets the field delimiter for the CSV.
+     * Needs to be called before opening the reader.
+     *
+     * @param string $fieldDelimiter Character that delimits fields
+     * @return Reader
+     */
+    public function setFieldDelimiter($fieldDelimiter)
+    {
+        $this->fieldDelimiter = $fieldDelimiter;
+        return $this;
+    }
+
+    /**
+     * Sets the field enclosure for the CSV.
+     * Needs to be called before opening the reader.
+     *
+     * @param string $fieldEnclosure Character that enclose fields
+     * @return Reader
+     */
+    public function setFieldEnclosure($fieldEnclosure)
+    {
+        $this->fieldEnclosure = $fieldEnclosure;
+        return $this;
+    }
+
+    /**
+     * Opens the file at the given path to make it ready to be read.
+     * The file must be UTF-8 encoded.
+     * @TODO add encoding detection/conversion
+     *
+     * @param  string $filePath Path of the CSV file to be read
+     * @return void
+     * @throws \Box\Spout\Common\Exception\IOException
+     */
+    protected function openReader($filePath)
+    {
+        $this->filePointer = $this->globalFunctionsHelper->fopen($filePath, 'r');
+        if (!$this->filePointer) {
+            throw new IOException('Could not open file ' . $filePath . ' for reading.');
+        }
+
+        $this->sheetIterator = new SheetIterator($this->filePointer, $this->fieldDelimiter, $this->fieldEnclosure, $this->globalFunctionsHelper);
+    }
+
+    /**
+     * Returns an iterator to iterate over sheets.
+     *
+     * @return SheetIterator To iterate over sheets
+     */
+    public function getConcreteSheetIterator()
+    {
+        return $this->sheetIterator;
+    }
+
+
+    /**
+     * Closes the reader. To be used after reading the file.
+     *
+     * @return void
+     */
+    protected function closeReader()
+    {
+        if ($this->filePointer) {
+            $this->globalFunctionsHelper->fclose($this->filePointer);
+        }
+    }
+}
diff --git a/src/Spout/Reader/CSV/RowIterator.php b/src/Spout/Reader/CSV/RowIterator.php
new file mode 100644
index 0000000..ffb533f
--- /dev/null
+++ b/src/Spout/Reader/CSV/RowIterator.php
@@ -0,0 +1,163 @@
+<?php
+
+namespace Box\Spout\Reader\CSV;
+
+use Box\Spout\Reader\IteratorInterface;
+
+/**
+ * Class RowIterator
+ * Iterate over CSV rows.
+ *
+ * @package Box\Spout\Reader\CSV
+ */
+class RowIterator implements IteratorInterface
+{
+    const UTF8_BOM = "\xEF\xBB\xBF";
+
+    /** @var resource Pointer to the CSV file to read */
+    protected $filePointer;
+
+    /** @var int Number of read rows */
+    protected $numReadRows = 0;
+
+    /** @var array|null Buffer used to store the row data, while checking if there are more rows to read */
+    protected $rowDataBuffer = null;
+
+    /** @var bool Indicates whether all rows have been read */
+    protected $hasReachedEndOfFile = false;
+
+    /** @var string Defines the character used to delimit fields (one character only) */
+    protected $fieldDelimiter = ',';
+
+    /** @var string Defines the character used to enclose fields (one character only) */
+    protected $fieldEnclosure = '"';
+
+    /** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
+    protected $globalFunctionsHelper;
+
+    /**
+     * @param resource $filePointer Pointer to the CSV file to read
+     * @param string $fieldDelimiter Character that delimits fields
+     * @param string $fieldEnclosure Character that enclose fields
+     * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
+     */
+    public function __construct($filePointer, $fieldDelimiter, $fieldEnclosure, $globalFunctionsHelper)
+    {
+        $this->filePointer = $filePointer;
+        $this->fieldDelimiter = $fieldDelimiter;
+        $this->fieldEnclosure = $fieldEnclosure;
+        $this->globalFunctionsHelper = $globalFunctionsHelper;
+    }
+
+    /**
+     * Rewind the Iterator to the first element
+     * @link http://php.net/manual/en/iterator.rewind.php
+     *
+     * @return void
+     */
+    public function rewind()
+    {
+        $this->rewindAndSkipUtf8Bom();
+
+        $this->numReadRows = 0;
+        $this->rowDataBuffer = null;
+
+        $this->next();
+    }
+
+    /**
+     * This rewinds and skips the UTF-8 BOM if inserted at the beginning of the file
+     * by moving the file pointer after it, so that it is not read.
+     *
+     * @return void
+     */
+    protected function rewindAndSkipUtf8Bom()
+    {
+        $this->globalFunctionsHelper->rewind($this->filePointer);
+
+        $hasUtf8Bom = ($this->globalFunctionsHelper->fgets($this->filePointer, 4) === self::UTF8_BOM);
+
+        if ($hasUtf8Bom) {
+            // we skip the 2 first bytes (so start from the 3rd byte)
+            $this->globalFunctionsHelper->fseek($this->filePointer, 3);
+        } else {
+            // if no BOM, reset the pointer to read from the beginning
+            $this->globalFunctionsHelper->fseek($this->filePointer, 0);
+        }
+    }
+
+    /**
+     * Checks if current position is valid
+     * @link http://php.net/manual/en/iterator.valid.php
+     *
+     * @return boolean
+     */
+    public function valid()
+    {
+        return ($this->filePointer && !$this->hasReachedEndOfFile);
+    }
+
+    /**
+     * Move forward to next element. Empty rows are skipped.
+     * @link http://php.net/manual/en/iterator.next.php
+     *
+     * @return void
+     */
+    public function next()
+    {
+        $lineData = null;
+        $this->hasReachedEndOfFile = feof($this->filePointer);
+
+        if (!$this->hasReachedEndOfFile) {
+            do {
+               $lineData = $this->globalFunctionsHelper->fgetcsv($this->filePointer, 0, $this->fieldDelimiter, $this->fieldEnclosure);
+           } while ($lineData === false || ($lineData !== null && $this->isEmptyLine($lineData)));
+
+            if ($lineData !== false && $lineData !== null) {
+                $this->rowDataBuffer = $lineData;
+                $this->numReadRows++;
+            }
+        }
+    }
+
+    /**
+     * @param array $lineData Array containing the cells value for the line
+     * @return bool Whether the given line is empty
+     */
+    protected function isEmptyLine($lineData)
+    {
+        return (count($lineData) === 1 && $lineData[0] === null);
+    }
+
+    /**
+     * Return the current element from the buffer
+     * @link http://php.net/manual/en/iterator.current.php
+     *
+     * @return array|null
+     */
+    public function current()
+    {
+        return $this->rowDataBuffer;
+    }
+
+    /**
+     * Return the key of the current element
+     * @link http://php.net/manual/en/iterator.key.php
+     *
+     * @return int
+     */
+    public function key()
+    {
+        return $this->numReadRows;
+    }
+
+    /**
+     * Cleans up what was created to iterate over the object.
+     *
+     * @return void
+     */
+    public function end()
+    {
+        // do nothing
+    }
+}
diff --git a/src/Spout/Reader/CSV/Sheet.php b/src/Spout/Reader/CSV/Sheet.php
new file mode 100644
index 0000000..207fcae
--- /dev/null
+++ b/src/Spout/Reader/CSV/Sheet.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace Box\Spout\Reader\CSV;
+
+use Box\Spout\Reader\SheetInterface;
+
+/**
+ * Class Sheet
+ *
+ * @package Box\Spout\Reader\CSV
+ */
+class Sheet implements SheetInterface
+{
+    /** @var RowIterator To iterate over the CSV's rows */
+    protected $rowIterator;
+
+    /**
+     * @param resource $filePointer Pointer to the CSV file to read
+     * @param string $fieldDelimiter Character that delimits fields
+     * @param string $fieldEnclosure Character that enclose fields
+     * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
+     */
+    public function __construct($filePointer, $fieldDelimiter, $fieldEnclosure, $globalFunctionsHelper)
+    {
+        $this->rowIterator = new RowIterator($filePointer, $fieldDelimiter, $fieldEnclosure, $globalFunctionsHelper);
+    }
+
+    /**
+     * @return RowIterator
+     */
+    public function getRowIterator()
+    {
+        return $this->rowIterator;
+    }
+}
diff --git a/src/Spout/Reader/CSV/SheetIterator.php b/src/Spout/Reader/CSV/SheetIterator.php
new file mode 100644
index 0000000..f424cd8
--- /dev/null
+++ b/src/Spout/Reader/CSV/SheetIterator.php
@@ -0,0 +1,96 @@
+<?php
+
+namespace Box\Spout\Reader\CSV;
+
+use Box\Spout\Reader\IteratorInterface;
+
+/**
+ * Class SheetIterator
+ * Iterate over CSV unique "sheet".
+ *
+ * @package Box\Spout\Reader\CSV
+ */
+class SheetIterator implements IteratorInterface
+{
+    /** @var Sheet The CSV unique "sheet" */
+    protected $sheet;
+
+    /** @var bool Whether the unique "sheet" has already been read */
+    protected $hasReadUniqueSheet = false;
+
+    /**
+     * @param resource $filePointer
+     * @param string $fieldDelimiter Character that delimits fields
+     * @param string $fieldEnclosure Character that enclose fields
+     * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
+     */
+    public function __construct($filePointer, $fieldDelimiter, $fieldEnclosure, $globalFunctionsHelper)
+    {
+        $this->sheet = new Sheet($filePointer, $fieldDelimiter, $fieldEnclosure, $globalFunctionsHelper);
+    }
+
+    /**
+     * Rewind the Iterator to the first element
+     * @link http://php.net/manual/en/iterator.rewind.php
+     *
+     * @return void
+     */
+    public function rewind()
+    {
+        $this->hasReadUniqueSheet = false;
+    }
+
+    /**
+     * Checks if current position is valid
+     * @link http://php.net/manual/en/iterator.valid.php
+     *
+     * @return boolean
+     */
+    public function valid()
+    {
+        return (!$this->hasReadUniqueSheet);
+    }
+
+    /**
+     * Move forward to next element
+     * @link http://php.net/manual/en/iterator.next.php
+     *
+     * @return void
+     */
+    public function next()
+    {
+        $this->hasReadUniqueSheet = true;
+    }
+
+    /**
+     * Return the current element
+     * @link http://php.net/manual/en/iterator.current.php
+     *
+     * @return Sheet
+     */
+    public function current()
+    {
+        return $this->sheet;
+    }
+
+    /**
+     * Return the key of the current element
+     * @link http://php.net/manual/en/iterator.key.php
+     *
+     * @return int
+     */
+    public function key()
+    {
+        return 1;
+    }
+
+    /**
+     * Cleans up what was created to iterate over the object.
+     *
+     * @return void
+     */
+    public function end()
+    {
+        // do nothing
+    }
+}
diff --git a/src/Spout/Reader/Exception/EndOfWorksheetsReachedException.php b/src/Spout/Reader/Exception/EndOfWorksheetsReachedException.php
deleted file mode 100644
index f2000c0..0000000
--- a/src/Spout/Reader/Exception/EndOfWorksheetsReachedException.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-namespace Box\Spout\Reader\Exception;
-
-/**
- * Class EndOfWorksheetsReachedException
- *
- * @package Box\Spout\Reader\Exception
- */
-class EndOfWorksheetsReachedException extends ReaderException
-{
-}
diff --git a/src/Spout/Reader/Exception/EndOfFileReachedException.php b/src/Spout/Reader/Exception/NoSheetsFoundException.php
similarity index 52%
rename from src/Spout/Reader/Exception/EndOfFileReachedException.php
rename to src/Spout/Reader/Exception/NoSheetsFoundException.php
index 6194d49..dfc4907 100644
--- a/src/Spout/Reader/Exception/EndOfFileReachedException.php
+++ b/src/Spout/Reader/Exception/NoSheetsFoundException.php
@@ -3,10 +3,10 @@
 namespace Box\Spout\Reader\Exception;
 
 /**
- * Class EndOfFileReachedException
+ * Class NoSheetsFoundException
  *
  * @package Box\Spout\Reader\Exception
  */
-class EndOfFileReachedException extends ReaderException
+class NoSheetsFoundException extends ReaderException
 {
 }
diff --git a/src/Spout/Reader/Exception/NoWorksheetsFoundException.php b/src/Spout/Reader/Exception/NoWorksheetsFoundException.php
deleted file mode 100644
index 91ea19c..0000000
--- a/src/Spout/Reader/Exception/NoWorksheetsFoundException.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-namespace Box\Spout\Reader\Exception;
-
-/**
- * Class NoWorksheetsFoundException
- *
- * @package Box\Spout\Reader\Exception
- */
-class NoWorksheetsFoundException extends ReaderException
-{
-}
diff --git a/src/Spout/Reader/Internal/XLSX/Worksheet.php b/src/Spout/Reader/Internal/XLSX/Worksheet.php
deleted file mode 100644
index 5145c28..0000000
--- a/src/Spout/Reader/Internal/XLSX/Worksheet.php
+++ /dev/null
@@ -1,58 +0,0 @@
-<?php
-
-namespace Box\Spout\Reader\Internal\XLSX;
-
-/**
- * Class Worksheet
- * Represents a worksheet within a XLSX file
- *
- * @package Box\Spout\Reader\Internal\XLSX
- */
-class Worksheet
-{
-    /** @var \Box\Spout\Reader\Sheet The "external" sheet */
-    protected $externalSheet;
-
-    /** @var int Worksheet index, based on the order of appareance in [Content_Types].xml (zero-based) */
-    protected $worksheetIndex;
-
-    /** @var string Path of the XML file containing the worksheet data */
-    protected $dataXmlFilePath;
-
-    /**\
-     * @param \Box\Spout\Reader\Sheet $externalSheet The associated "external" sheet
-     * @param int $worksheetIndex Worksheet index, based on the order of appareance in [Content_Types].xml (zero-based)
-     * @param string $dataXmlFilePath Path of the XML file containing the worksheet data
-     */
-    public function __construct($externalSheet, $worksheetIndex, $dataXmlFilePath)
-    {
-        $this->externalSheet = $externalSheet;
-        $this->worksheetIndex = $worksheetIndex;
-        $this->dataXmlFilePath = $dataXmlFilePath;
-    }
-
-    /**
-     * @return string Path of the XML file containing the worksheet data,
-     *                without the leading slash.
-     */
-    public function getDataXmlFilePath()
-    {
-        return ltrim($this->dataXmlFilePath, '/');
-    }
-
-    /**
-     * @return \Box\Spout\Reader\Sheet The "external" sheet
-     */
-    public function getExternalSheet()
-    {
-        return $this->externalSheet;
-    }
-
-    /**
-     * @return int
-     */
-    public function getWorksheetIndex()
-    {
-        return $this->worksheetIndex;
-    }
-}
diff --git a/src/Spout/Reader/IteratorInterface.php b/src/Spout/Reader/IteratorInterface.php
new file mode 100644
index 0000000..7d58e28
--- /dev/null
+++ b/src/Spout/Reader/IteratorInterface.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Box\Spout\Reader;
+
+/**
+ * Interface IteratorInterface
+ *
+ * @package Box\Spout\Reader
+ */
+interface IteratorInterface extends \Iterator
+{
+    /**
+     * Cleans up what was created to iterate over the object.
+     *
+     * @return void
+     */
+    public function end();
+}
diff --git a/src/Spout/Reader/ReaderFactory.php b/src/Spout/Reader/ReaderFactory.php
index 9766978..0e39f59 100644
--- a/src/Spout/Reader/ReaderFactory.php
+++ b/src/Spout/Reader/ReaderFactory.php
@@ -19,7 +19,7 @@ class ReaderFactory
      * This creates an instance of the appropriate reader, given the type of the file to be read
      *
      * @param  string $readerType Type of the reader to instantiate
-     * @return \Box\Spout\Reader\CSV|\Box\Spout\Reader\XLSX
+     * @return ReaderInterface
      * @throws \Box\Spout\Common\Exception\UnsupportedTypeException
      */
     public static function create($readerType)
@@ -28,10 +28,10 @@ class ReaderFactory
 
         switch ($readerType) {
             case Type::CSV:
-                $reader = new CSV();
+                $reader = new CSV\Reader();
                 break;
             case Type::XLSX:
-                $reader = new XLSX();
+                $reader = new XLSX\Reader();
                 break;
             default:
                 throw new UnsupportedTypeException('No readers supporting the given type: ' . $readerType);
diff --git a/src/Spout/Reader/ReaderInterface.php b/src/Spout/Reader/ReaderInterface.php
index 7253821..8ecde30 100644
--- a/src/Spout/Reader/ReaderInterface.php
+++ b/src/Spout/Reader/ReaderInterface.php
@@ -20,26 +20,12 @@ interface ReaderInterface
     public function open($filePath);
 
     /**
-     * Returns whether all rows have been read (i.e. if we are at the end of the file).
-     * To know if the end of file has been reached, it uses a buffer. If the buffer is
-     * empty (meaning, nothing has been read or previous read line has been consumed), then
-     * it reads the next line, store it in the buffer for the next time or flip a variable if
-     * the end of file has been reached.
+     * Returns an iterator to iterate over sheets.
      *
-     * @return bool
-     * @throws \Box\Spout\Common\Exception\IOException If the stream was not opened first
+     * @return \Iterator To iterate over sheets
+     * @throws \Box\Spout\Reader\Exception\ReaderNotOpenedException If called before opening the reader
      */
-    public function hasNextRow();
-
-    /**
-     * Returns next row if available. The row is either retrieved from the buffer if it is not empty or fetched by
-     * actually reading the file.
-     *
-     * @return array Array that contains the data for the read row
-     * @throws \Box\Spout\Common\Exception\IOException If the stream was not opened first
-     * @throws \Box\Spout\Reader\Exception\EndOfFileReachedException
-     */
-    public function nextRow();
+    public function getSheetIterator();
 
     /**
      * Closes the reader, preventing any additional reading
diff --git a/src/Spout/Reader/SheetInterface.php b/src/Spout/Reader/SheetInterface.php
new file mode 100644
index 0000000..bc19078
--- /dev/null
+++ b/src/Spout/Reader/SheetInterface.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Box\Spout\Reader;
+
+/**
+ * Interface SheetInterface
+ *
+ * @package Box\Spout\Reader
+ */
+interface SheetInterface
+{
+    /**
+     * Returns an iterator to iterate over the sheet's rows.
+     *
+     * @return \Iterator
+     */
+    public function getRowIterator();
+}
diff --git a/src/Spout/Reader/XLSX.php b/src/Spout/Reader/XLSX.php
deleted file mode 100644
index 7f176fe..0000000
--- a/src/Spout/Reader/XLSX.php
+++ /dev/null
@@ -1,394 +0,0 @@
-<?php
-
-namespace Box\Spout\Reader;
-
-use Box\Spout\Common\Exception\BadUsageException;
-use Box\Spout\Common\Exception\IOException;
-use Box\Spout\Reader\Exception\EndOfWorksheetsReachedException;
-use Box\Spout\Reader\Exception\NoWorksheetsFoundException;
-use Box\Spout\Reader\Exception\ReaderNotOpenedException;
-use Box\Spout\Reader\Helper\XLSX\CellHelper;
-use Box\Spout\Reader\Helper\XLSX\SharedStringsHelper;
-use Box\Spout\Reader\Helper\XLSX\WorksheetHelper;
-
-/**
- * Class XLSX
- * This class provides support to read data from a XLSX file
- *
- * @package Box\Spout\Reader
- */
-class XLSX extends AbstractReader
-{
-    const CELL_TYPE_INLINE_STRING = 'inlineStr';
-    const CELL_TYPE_STR = 'str';
-    const CELL_TYPE_SHARED_STRING = 's';
-    const CELL_TYPE_BOOLEAN = 'b';
-    const CELL_TYPE_NUMERIC = 'n';
-    const CELL_TYPE_DATE = 'd';
-    const CELL_TYPE_ERROR = 'e';
-    
-    /** @var string Real path of the file to read */
-    protected $filePath;
-
-    /** @var string Temporary folder where the temporary files will be created */
-    protected $tempFolder;
-
-    /** @var \ZipArchive */
-    protected $zip;
-
-    /** @var Helper\XLSX\SharedStringsHelper Helper to work with shared strings */
-    protected $sharedStringsHelper;
-
-    /** @var Helper\XLSX\WorksheetHelper Helper to work with worksheets */
-    protected $worksheetHelper;
-
-    /** @var Internal\XLSX\Worksheet[] The list of worksheets present in the file */
-    protected $worksheets;
-
-    /** @var Internal\XLSX\Worksheet The worksheet being read */
-    protected $currentWorksheet;
-
-    /** @var \XMLReader The XMLReader object that will help read sheets XML data */
-    protected $xmlReader;
-
-    /** @var int The number of columns the worksheet has (0 meaning undefined) */
-    protected $numberOfColumns = 0;
-
-    /**
-     * @param string $tempFolder Temporary folder where the temporary files will be created
-     * @return XLSX
-     */
-    public function setTempFolder($tempFolder)
-    {
-        $this->tempFolder = $tempFolder;
-        return $this;
-    }
-
-    /**
-     * Opens the file at the given file path to make it ready to be read.
-     * It also parses the sharedStrings.xml file to get all the shared strings available in memory
-     * and fetches all the available worksheets.
-     *
-     * @param  string $filePath Path of the file to be read
-     * @return void
-     * @throws \Box\Spout\Common\Exception\IOException If the file at the given path or its content cannot be read
-     * @throws Exception\NoWorksheetsFoundException If there are no worksheets in the file
-     */
-    protected function openReader($filePath)
-    {
-        $this->filePath = $filePath;
-        $this->zip = new \ZipArchive();
-
-        if ($this->zip->open($filePath) === true) {
-            $this->sharedStringsHelper = new SharedStringsHelper($filePath, $this->tempFolder);
-
-            if ($this->sharedStringsHelper->hasSharedStrings()) {
-                // Extracts all the strings from the worksheets for easy access in the future
-                $this->sharedStringsHelper->extractSharedStrings();
-            }
-
-            // Fetch all available worksheets
-            $this->worksheetHelper = new WorksheetHelper($filePath, $this->globalFunctionsHelper);
-            $this->worksheets = $this->worksheetHelper->getWorksheets($filePath);
-
-            if (count($this->worksheets) === 0) {
-                throw new NoWorksheetsFoundException('The file must contain at least one worksheet.');
-            }
-        } else {
-            throw new IOException('Could not open ' . $filePath . ' for reading.');
-        }
-    }
-
-    /**
-     * Returns whether another worksheet exists after the current worksheet.
-     *
-     * @return bool Whether another worksheet exists after the current worksheet.
-     * @throws Exception\ReaderNotOpenedException If the stream was not opened first
-     */
-    public function hasNextSheet()
-    {
-        if (!$this->isStreamOpened) {
-            throw new ReaderNotOpenedException('Stream should be opened first.');
-        }
-
-        return $this->worksheetHelper->hasNextWorksheet($this->currentWorksheet, $this->worksheets);
-    }
-
-    /**
-     * Moves the pointer to the current worksheet.
-     * Moving to another worksheet will stop the reading in the current worksheet.
-     *
-     * @return \Box\Spout\Reader\Sheet The next sheet
-     * @throws Exception\ReaderNotOpenedException If the stream was not opened first
-     * @throws Exception\EndOfWorksheetsReachedException If there is no more worksheets to read
-     */
-    public function nextSheet()
-    {
-        if (!$this->hasNextSheet()) {
-            throw new EndOfWorksheetsReachedException('End of worksheets was reached. Cannot read more worksheets.');
-        }
-
-        if ($this->currentWorksheet === null) {
-            $nextWorksheet = $this->worksheets[0];
-        } else {
-            $currentWorksheetIndex = $this->currentWorksheet->getWorksheetIndex();
-            $nextWorksheet = $this->worksheets[$currentWorksheetIndex + 1];
-        }
-
-        $this->initXmlReaderForWorksheetData($nextWorksheet);
-        $this->currentWorksheet = $nextWorksheet;
-
-        // make sure that we are ready to read more rows
-        $this->hasReachedEndOfFile = false;
-        $this->emptyRowDataBuffer();
-
-        return $this->currentWorksheet->getExternalSheet();
-    }
-
-    /**
-     * Initializes the XMLReader object that reads worksheet data for the given worksheet.
-     * If another worksheet was being read, it closes the reader before reopening it for the new worksheet.
-     * The XMLReader is configured to be safe from billion laughs attack.
-     *
-     * @param Internal\XLSX\Worksheet $worksheet The worksheet to initialize the XMLReader with
-     * @return void
-     * @throws \Box\Spout\Common\Exception\IOException If the worksheet data XML cannot be read
-     */
-    protected function initXmlReaderForWorksheetData($worksheet)
-    {
-        // if changing worksheet and the XMLReader was initialized for the current worksheet
-        if ($worksheet != $this->currentWorksheet && $this->xmlReader) {
-            $this->xmlReader->close();
-        } else if (!$this->xmlReader) {
-            $this->xmlReader = new \XMLReader();
-        }
-
-        $worksheetDataXMLFilePath = $worksheet->getDataXmlFilePath();
-
-        $worksheetDataFilePath = 'zip://' . $this->filePath . '#' . $worksheetDataXMLFilePath;
-        if ($this->xmlReader->open($worksheetDataFilePath, null, LIBXML_NONET) === false) {
-            throw new IOException('Could not open "' . $worksheetDataXMLFilePath . '".');
-        }
-    }
-
-    /**
-     * Reads and returns data of the line that comes after the last read line, on the current worksheet.
-     * Empty rows will be skipped.
-     *
-     * @return array|null Array that contains the data for the read line or null at the end of the file
-     * @throws \Box\Spout\Common\Exception\BadUsageException If the pointer to the current worksheet has not been set
-     * @throws \Box\Spout\Reader\Exception\SharedStringNotFoundException If a shared string was not found
-     */
-    protected function read()
-    {
-        if (!$this->currentWorksheet) {
-            throw new BadUsageException('You must call nextSheet() before calling hasNextRow() or nextRow()');
-        }
-
-        $escaper = new \Box\Spout\Common\Escaper\XLSX();
-        $isInsideRowTag = false;
-        $rowData = [];
-
-        while ($this->xmlReader->read()) {
-            if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === 'dimension') {
-                // Read dimensions of the worksheet
-                $dimensionRef = $this->xmlReader->getAttribute('ref'); // returns 'A1:M13' for instance (or 'A1' for empty sheet)
-                if (preg_match('/[A-Z\d]+:([A-Z\d]+)/', $dimensionRef, $matches)) {
-                    $lastCellIndex = $matches[1];
-                    $this->numberOfColumns = CellHelper::getColumnIndexFromCellIndex($lastCellIndex) + 1;
-                }
-
-            } else if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === 'row') {
-                // Start of the row description
-                $isInsideRowTag = true;
-
-                // Read spans info if present
-                $numberOfColumnsForRow = $this->numberOfColumns;
-                $spans = $this->xmlReader->getAttribute('spans'); // returns '1:5' for instance
-                if ($spans) {
-                    list(, $numberOfColumnsForRow) = explode(':', $spans);
-                    $numberOfColumnsForRow = intval($numberOfColumnsForRow);
-                }
-                $rowData = ($numberOfColumnsForRow !== 0) ? array_fill(0, $numberOfColumnsForRow, '') : [];
-
-            } else if ($isInsideRowTag && $this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === 'c') {
-                // Start of a cell description
-                $currentCellIndex = $this->xmlReader->getAttribute('r');
-                $currentColumnIndex = CellHelper::getColumnIndexFromCellIndex($currentCellIndex);
-
-                $node = $this->xmlReader->expand();
-                $rowData[$currentColumnIndex] = $this->getCellValue($node, $escaper);
-
-            } else if ($this->xmlReader->nodeType == \XMLReader::END_ELEMENT && $this->xmlReader->name === 'row') {
-                // End of the row description
-                // If needed, we fill the empty cells
-                $rowData = ($this->numberOfColumns !== 0) ? $rowData : CellHelper::fillMissingArrayIndexes($rowData);
-                break;
-            }
-        }
-
-        // no data means "end of file"
-        return ($rowData !== []) ? $rowData : null;
-    }
-
-    /**
-     * Returns the cell's string value from a node's nested value node
-     *
-     * @param \DOMNode $node
-     * @return string The value associated with the cell
-     */
-    protected function getVNodeValue($node)
-    {
-        // for cell types having a "v" tag containing the value.
-        // if not, the returned value should be empty string.
-        $vNode = $node->getElementsByTagName('v')->item(0);
-        if ($vNode !== null) {
-            return $vNode->nodeValue;
-        }
-        return "";
-    }
-
-    /**
-     * Returns the cell String value where string is inline.
-     *
-     * @param \DOMNode $node
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return string The value associated with the cell (null when the cell has an error)
-     */
-    protected function formatInlineStringCellValue($node, $escaper)
-    {
-        // inline strings are formatted this way:
-        // <c r="A1" t="inlineStr"><is><t>[INLINE_STRING]</t></is></c>
-        $tNode = $node->getElementsByTagName('t')->item(0);
-        $escapedCellValue = trim($tNode->nodeValue);
-        $cellValue = $escaper->unescape($escapedCellValue);
-        return $cellValue;
-    }
-
-    /**
-     * Returns the cell String value from shared-strings file using nodeValue index.
-     *
-     * @param string $nodeValue
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return string The value associated with the cell (null when the cell has an error)
-     */
-    protected function formatSharedStringCellValue($nodeValue, $escaper)
-    {
-        // shared strings are formatted this way:
-        // <c r="A1" t="s"><v>[SHARED_STRING_INDEX]</v></c>
-        $sharedStringIndex = intval($nodeValue);
-        $escapedCellValue = $this->sharedStringsHelper->getStringAtIndex($sharedStringIndex);
-        $cellValue = $escaper->unescape($escapedCellValue);
-        return $cellValue;
-    }
-
-    /**
-     * Returns the cell String value, where string is stored in value node.
-     *
-     * @param string $nodeValue
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return string The value associated with the cell (null when the cell has an error)
-     */
-    protected function formatStrCellValue($nodeValue, $escaper)
-    {
-        $escapedCellValue = trim($nodeValue);
-        $cellValue = $escaper->unescape($escapedCellValue);
-        return $cellValue;
-    }
-
-    /**
-     * Returns the cell Numeric value from string of nodeValue.
-     *
-     * @param string $nodeValue
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return int|float The value associated with the cell
-     */
-    protected function formatNumericCellValue($nodeValue)
-    {
-        $cellValue = is_int($nodeValue) ? intval($nodeValue) : floatval($nodeValue);
-        return $cellValue;
-    }
-
-    /**
-     * Returns the cell Boolean value from a specific node's Value.
-     *
-     * @param string $nodeValue
-     * @return bool The value associated with the cell
-     */
-    protected function formatBooleanCellValue($nodeValue)
-    {
-        // !! is similar to boolval()
-        $cellValue = !!$nodeValue;
-        return $cellValue;
-    }
-
-    /**
-     * Returns a cell's PHP Date value, associated to the given stored nodeValue.
-     *
-     * @param string $nodeValue
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return DateTime|null The value associated with the cell (null when the cell has an error)
-     */
-    protected function formatDateCellValue($nodeValue)
-    {
-        try { // Mitigate thrown Exception on invalid date-time format (http://php.net/manual/en/datetime.construct.php)
-            $cellValue = new \DateTime($nodeValue);
-            return $cellValue;
-        } catch (\Exception $e) {
-            return null;
-        }
-    }
-
-    /**
-     * Returns the (unescaped) correctly marshalled, cell value associated to the given XML node.
-     *
-     * @param \DOMNode $node
-     * @param \Box\Spout\Common\Escaper\XLSX $escaper
-     * @return string|int|float|bool|null The value associated with the cell (null when the cell has an error)
-     */
-    protected function getCellValue($node, $escaper)
-    {
-        // Default cell type is "n"
-        $cellType = $node->getAttribute('t') ?: 'n';
-        $vNodeValue = $this->getVNodeValue($node);
-        if ( ($vNodeValue === "") && ($cellType !== self::CELL_TYPE_INLINE_STRING) ) {
-            return $vNodeValue;
-        }
-
-        switch ($cellType)
-        {
-            case self::CELL_TYPE_INLINE_STRING:
-                return $this->formatInlineStringCellValue($node, $escaper);
-            case self::CELL_TYPE_SHARED_STRING:
-                return $this->formatSharedStringCellValue($vNodeValue, $escaper);
-            case self::CELL_TYPE_STR:
-                return $this->formatStrCellValue($vNodeValue, $escaper);
-            case self::CELL_TYPE_BOOLEAN:
-                return $this->formatBooleanCellValue($vNodeValue);
-            case self::CELL_TYPE_NUMERIC:
-                return $this->formatNumericCellValue($vNodeValue);
-            case self::CELL_TYPE_DATE:
-                return $this->formatDateCellValue($vNodeValue);
-            default:
-                return null;
-        }
-    }
-
-    /**
-     * Closes the reader. To be used after reading the file.
-     *
-     * @return void
-     */
-    protected function closeReader()
-    {
-        if ($this->xmlReader) {
-            $this->xmlReader->close();
-        }
-
-        if ($this->zip) {
-            $this->zip->close();
-        }
-
-        $this->sharedStringsHelper->cleanup();
-    }
-}
diff --git a/src/Spout/Reader/Helper/XLSX/CellHelper.php b/src/Spout/Reader/XLSX/Helper/CellHelper.php
similarity index 97%
rename from src/Spout/Reader/Helper/XLSX/CellHelper.php
rename to src/Spout/Reader/XLSX/Helper/CellHelper.php
index 7125ded..d2d31e8 100644
--- a/src/Spout/Reader/Helper/XLSX/CellHelper.php
+++ b/src/Spout/Reader/XLSX/Helper/CellHelper.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX;
+namespace Box\Spout\Reader\XLSX\Helper;
 
 use Box\Spout\Common\Exception\InvalidArgumentException;
 
@@ -8,7 +8,7 @@ use Box\Spout\Common\Exception\InvalidArgumentException;
  * Class CellHelper
  * This class provides helper functions when working with cells
  *
- * @package Box\Spout\Reader\Helper\XLSX
+ * @package Box\Spout\Reader\XLSX\Helper
  */
 class CellHelper
 {
diff --git a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactory.php b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactory.php
similarity index 97%
rename from src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactory.php
rename to src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactory.php
index 642647a..8fffdb0 100644
--- a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactory.php
+++ b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactory.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX\SharedStringsCaching;
+namespace Box\Spout\Reader\XLSX\Helper\SharedStringsCaching;
 
 /**
  * Class CachingStrategyFactory
  *
- * @package Box\Spout\Reader\Helper\XLSX\SharedStringsCaching
+ * @package Box\Spout\Reader\XLSX\Helper\SharedStringsCaching
  */
 class CachingStrategyFactory
 {
diff --git a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyInterface.php b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyInterface.php
similarity index 90%
rename from src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyInterface.php
rename to src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyInterface.php
index 4334d86..631222a 100644
--- a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyInterface.php
+++ b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyInterface.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX\SharedStringsCaching;
+namespace Box\Spout\Reader\XLSX\Helper\SharedStringsCaching;
 
 /**
  * Interface CachingStrategyInterface
  *
- * @package Box\Spout\Reader\Helper\XLSX\SharedStringsCaching
+ * @package Box\Spout\Reader\XLSX\Helper\SharedStringsCaching
  */
 interface CachingStrategyInterface
 {
diff --git a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/FileBasedStrategy.php b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/FileBasedStrategy.php
similarity index 95%
rename from src/Spout/Reader/Helper/XLSX/SharedStringsCaching/FileBasedStrategy.php
rename to src/Spout/Reader/XLSX/Helper/SharedStringsCaching/FileBasedStrategy.php
index f9374e7..9f1f19f 100644
--- a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/FileBasedStrategy.php
+++ b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/FileBasedStrategy.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX\SharedStringsCaching;
+namespace Box\Spout\Reader\XLSX\Helper\SharedStringsCaching;
 
 use Box\Spout\Common\Helper\FileSystemHelper;
 use Box\Spout\Common\Helper\GlobalFunctionsHelper;
@@ -13,7 +13,7 @@ use Box\Spout\Reader\Exception\SharedStringNotFoundException;
  * Shared strings are stored in small files (with a max number of strings per file).
  * This strategy is slower than an in-memory strategy but is used to avoid out of memory crashes.
  *
- * @package Box\Spout\Reader\Helper\XLSX\SharedStringsCaching
+ * @package Box\Spout\Reader\XLSX\Helper\SharedStringsCaching
  */
 class FileBasedStrategy implements CachingStrategyInterface
 {
@@ -26,6 +26,9 @@ class FileBasedStrategy implements CachingStrategyInterface
     /** @var \Box\Spout\Common\Helper\FileSystemHelper Helper to perform file system operations */
     protected $fileSystemHelper;
 
+    /** @var string Temporary folder where the temporary files will be created */
+    protected $tempFolder;
+
     /**
      * @var int Maximum number of strings that can be stored in one temp file
      * @see CachingStrategyFactory::MAX_NUM_STRINGS_PER_TEMP_FILE
@@ -42,7 +45,7 @@ class FileBasedStrategy implements CachingStrategyInterface
     protected $inMemoryTempFilePath;
 
     /**
-     * @var string Contents of the temporary file that was last read
+     * @var array Contents of the temporary file that was last read
      * @see CachingStrategyFactory::MAX_NUM_STRINGS_PER_TEMP_FILE
      */
     protected $inMemoryTempFileContents;
diff --git a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/InMemoryStrategy.php b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/InMemoryStrategy.php
similarity index 95%
rename from src/Spout/Reader/Helper/XLSX/SharedStringsCaching/InMemoryStrategy.php
rename to src/Spout/Reader/XLSX/Helper/SharedStringsCaching/InMemoryStrategy.php
index 41b41be..c6a5321 100644
--- a/src/Spout/Reader/Helper/XLSX/SharedStringsCaching/InMemoryStrategy.php
+++ b/src/Spout/Reader/XLSX/Helper/SharedStringsCaching/InMemoryStrategy.php
@@ -1,6 +1,7 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX\SharedStringsCaching;
+namespace Box\Spout\Reader\XLSX\Helper\SharedStringsCaching;
+
 use Box\Spout\Reader\Exception\SharedStringNotFoundException;
 
 /**
@@ -9,7 +10,7 @@ use Box\Spout\Reader\Exception\SharedStringNotFoundException;
  * This class implements the in-memory caching strategy for shared strings.
  * This strategy is used when the number of unique strings is low, compared to the memory available.
  *
- * @package Box\Spout\Reader\Helper\XLSX\SharedStringsCaching
+ * @package Box\Spout\Reader\XLSX\Helper\SharedStringsCaching
  */
 class InMemoryStrategy implements CachingStrategyInterface
 {
diff --git a/src/Spout/Reader/Helper/XLSX/SharedStringsHelper.php b/src/Spout/Reader/XLSX/Helper/SharedStringsHelper.php
similarity index 95%
rename from src/Spout/Reader/Helper/XLSX/SharedStringsHelper.php
rename to src/Spout/Reader/XLSX/Helper/SharedStringsHelper.php
index 0f6d21d..75f8989 100644
--- a/src/Spout/Reader/Helper/XLSX/SharedStringsHelper.php
+++ b/src/Spout/Reader/XLSX/Helper/SharedStringsHelper.php
@@ -1,16 +1,16 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX;
+namespace Box\Spout\Reader\XLSX\Helper;
 
 use Box\Spout\Common\Exception\IOException;
-use Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyFactory;
-use Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyInterface;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyFactory;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyInterface;
 
 /**
  * Class SharedStringsHelper
  * This class provides helper functions for reading sharedStrings XML file
  *
- * @package Box\Spout\Reader\Helper\XLSX
+ * @package Box\Spout\Reader\XLSX\Helper
  */
 class SharedStringsHelper
 {
@@ -58,13 +58,13 @@ class SharedStringsHelper
     }
 
     /**
-     * Builds an in-memory array containing all the shared strings of the worksheet.
+     * Builds an in-memory array containing all the shared strings of the sheet.
      * All the strings are stored in a XML file, located at 'xl/sharedStrings.xml'.
-     * It is then accessed by the worksheet data, via the string index in the built table.
+     * It is then accessed by the sheet data, via the string index in the built table.
      *
      * More documentation available here: http://msdn.microsoft.com/en-us/library/office/gg278314.aspx
      *
-     * The XML file can be really big with worksheets containing a lot of data. That is why
+     * The XML file can be really big with sheets containing a lot of data. That is why
      * we need to use a XML reader that provides streaming like the XMLReader library.
      * Please note that SimpleXML does not provide such a functionality but since it is faster
      * and more handy to parse few XML nodes, it is used in combination with XMLReader for that purpose.
@@ -154,7 +154,8 @@ class SharedStringsHelper
 
         $readError = libxml_get_last_error();
         if ($readError !== false) {
-            throw new IOException("The sharedStrings.xml file is invalid and cannot be read. [{$readError->message}]");
+            $readErrorMessage = trim($readError->message);
+            throw new IOException("The sharedStrings.xml file is invalid and cannot be read. [{$readErrorMessage}]");
         }
 
         // reset the setting to display XML warnings/errors
diff --git a/src/Spout/Reader/Helper/XLSX/WorksheetHelper.php b/src/Spout/Reader/XLSX/Helper/SheetHelper.php
similarity index 78%
rename from src/Spout/Reader/Helper/XLSX/WorksheetHelper.php
rename to src/Spout/Reader/XLSX/Helper/SheetHelper.php
index d869dd4..a3431ae 100644
--- a/src/Spout/Reader/Helper/XLSX/WorksheetHelper.php
+++ b/src/Spout/Reader/XLSX/Helper/SheetHelper.php
@@ -1,17 +1,16 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX;
+namespace Box\Spout\Reader\XLSX\Helper;
 
-use Box\Spout\Reader\Internal\XLSX\Worksheet;
-use Box\Spout\Reader\Sheet;
+use Box\Spout\Reader\XLSX\Sheet;
 
 /**
- * Class WorksheetHelper
- * This class provides helper functions related to XLSX worksheets
+ * Class SheetHelper
+ * This class provides helper functions related to XLSX sheets
  *
- * @package Box\Spout\Reader\Helper\XLSX
+ * @package Box\Spout\Reader\XLSX\Helper
  */
-class WorksheetHelper
+class SheetHelper
 {
     /** Extension for XML files */
     const XML_EXTENSION = '.xml';
@@ -26,12 +25,15 @@ class WorksheetHelper
     const MAIN_NAMESPACE_FOR_WORKBOOK_XML_RELS = 'http://schemas.openxmlformats.org/package/2006/relationships';
     const MAIN_NAMESPACE_FOR_WORKBOOK_XML = 'http://schemas.openxmlformats.org/spreadsheetml/2006/main';
 
-    /** Value of the Override attribute used in [Content_Types].xml to define worksheets */
+    /** Value of the Override attribute used in [Content_Types].xml to define sheets */
     const OVERRIDE_CONTENT_TYPES_ATTRIBUTE = 'application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml';
 
     /** @var string Path of the XLSX file being read */
     protected $filePath;
 
+    /** @var \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper Helper to work with shared strings */
+    protected $sharedStringsHelper;
+
     /** @var \Box\Spout\Common\Helper\GlobalFunctionsHelper Helper to work with global functions */
     protected $globalFunctionsHelper;
 
@@ -43,41 +45,43 @@ class WorksheetHelper
 
     /**
      * @param string $filePath Path of the XLSX file being read
+     * @param \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper Helper to work with shared strings
      * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
      */
-    public function __construct($filePath, $globalFunctionsHelper)
+    public function __construct($filePath, $sharedStringsHelper, $globalFunctionsHelper)
     {
         $this->filePath = $filePath;
+        $this->sharedStringsHelper = $sharedStringsHelper;
         $this->globalFunctionsHelper = $globalFunctionsHelper;
     }
 
     /**
-     * Returns the file paths of the worksheet data XML files within the XLSX file.
-     * The paths are read from the [Content_Types].xml file.
+     * Returns the sheets metadata of the file located at the previously given file path.
+     * The paths to the sheets' data are read from the [Content_Types].xml file.
      *
-     * @return Worksheet[] Worksheets within the XLSX file
+     * @return Sheet[] Sheets within the XLSX file
      */
-    public function getWorksheets()
+    public function getSheets()
     {
-        $worksheets = [];
+        $sheets = [];
 
         $contentTypesAsXMLElement = $this->getFileAsXMLElementWithNamespace(
             self::CONTENT_TYPES_XML_FILE_PATH,
             self::MAIN_NAMESPACE_FOR_CONTENT_TYPES_XML
         );
 
-        // find all nodes defining a worksheet
+        // find all nodes defining a sheet
         $sheetNodes = $contentTypesAsXMLElement->xpath('//ns:Override[@ContentType="' . self::OVERRIDE_CONTENT_TYPES_ATTRIBUTE . '"]');
+        $numSheetNodes = count($sheetNodes);
 
-        for ($i = 0; $i < count($sheetNodes); $i++) {
+        for ($i = 0; $i < $numSheetNodes; $i++) {
             $sheetNode = $sheetNodes[$i];
             $sheetDataXMLFilePath = (string) $sheetNode->attributes()->PartName;
 
-            $sheet = $this->getSheet($sheetDataXMLFilePath, $i);
-            $worksheets[] = new Worksheet($sheet, $i, $sheetDataXMLFilePath);
+            $sheets[] = $this->getSheetFromXML($sheetDataXMLFilePath, $i);
         }
 
-        return $worksheets;
+        return $sheets;
     }
 
     /**
@@ -92,9 +96,9 @@ class WorksheetHelper
      *
      * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
      * @param int $sheetIndexZeroBased Index of the sheet, based on order in [Content_Types].xml (zero-based)
-     * @return \Box\Spout\Reader\Sheet Sheet instance
+     * @return \Box\Spout\Reader\XLSX\Sheet Sheet instance
      */
-    protected function getSheet($sheetDataXMLFilePath, $sheetIndexZeroBased)
+    protected function getSheetFromXML($sheetDataXMLFilePath, $sheetIndexZeroBased)
     {
         $sheetId = $sheetIndexZeroBased + 1;
         $sheetName = $this->getDefaultSheetName($sheetDataXMLFilePath);
@@ -126,14 +130,14 @@ class WorksheetHelper
             }
         }
 
-        return new Sheet($sheetId, $sheetIndexZeroBased, $sheetName);
+        return new Sheet($this->filePath, $sheetDataXMLFilePath, $this->sharedStringsHelper, $sheetId, $sheetIndexZeroBased, $sheetName);
     }
 
     /**
      * Returns the default name of the sheet whose data is located
      * at the given path.
      *
-     * @param $sheetDataXMLFilePath
+     * @param string $sheetDataXMLFilePath Path of the sheet data XML file
      * @return string The default sheet name
      */
     protected function getDefaultSheetName($sheetDataXMLFilePath)
@@ -193,17 +197,4 @@ class WorksheetHelper
 
         return $xmlElement;
     }
-
-    /**
-     * Returns whether another worksheet exists after the current worksheet.
-     * The order is determined by the order of appearance in the [Content_Types].xml file.
-     *
-     * @param Worksheet|null $currentWorksheet The worksheet being currently read or null if reading has not started yet
-     * @param Worksheet[] $allWorksheets A list of all worksheets in the XLSX file. Must contain at least one worksheet
-     * @return bool Whether another worksheet exists after the current sheet
-     */
-    public function hasNextWorksheet($currentWorksheet, $allWorksheets)
-    {
-        return ($currentWorksheet === null || ($currentWorksheet->getWorksheetIndex() + 1 < count($allWorksheets)));
-    }
 }
diff --git a/src/Spout/Reader/XLSX/Reader.php b/src/Spout/Reader/XLSX/Reader.php
new file mode 100644
index 0000000..f24d185
--- /dev/null
+++ b/src/Spout/Reader/XLSX/Reader.php
@@ -0,0 +1,93 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX;
+
+use Box\Spout\Common\Exception\IOException;
+use Box\Spout\Reader\AbstractReader;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsHelper;
+
+/**
+ * Class Reader
+ * This class provides support to read data from a XLSX file
+ *
+ * @package Box\Spout\Reader\XLSX
+ */
+class Reader extends AbstractReader
+{
+    /** @var string Temporary folder where the temporary files will be created */
+    protected $tempFolder;
+
+    /** @var \ZipArchive */
+    protected $zip;
+
+    /** @var \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper Helper to work with shared strings */
+    protected $sharedStringsHelper;
+
+    /** @var SheetIterator To iterator over the XLSX sheets */
+    protected $sheetIterator;
+
+
+    /**
+     * @param string $tempFolder Temporary folder where the temporary files will be created
+     * @return Reader
+     */
+    public function setTempFolder($tempFolder)
+    {
+        $this->tempFolder = $tempFolder;
+        return $this;
+    }
+
+    /**
+     * Opens the file at the given file path to make it ready to be read.
+     * It also parses the sharedStrings.xml file to get all the shared strings available in memory
+     * and fetches all the available sheets.
+     *
+     * @param  string $filePath Path of the file to be read
+     * @return void
+     * @throws \Box\Spout\Common\Exception\IOException If the file at the given path or its content cannot be read
+     * @throws \Box\Spout\Reader\Exception\NoSheetsFoundException If there are no sheets in the file
+     */
+    protected function openReader($filePath)
+    {
+        $this->zip = new \ZipArchive();
+
+        if ($this->zip->open($filePath) === true) {
+            $this->sharedStringsHelper = new SharedStringsHelper($filePath, $this->tempFolder);
+
+            if ($this->sharedStringsHelper->hasSharedStrings()) {
+                // Extracts all the strings from the sheets for easy access in the future
+                $this->sharedStringsHelper->extractSharedStrings();
+            }
+
+            $this->sheetIterator = new SheetIterator($filePath, $this->sharedStringsHelper, $this->globalFunctionsHelper);
+        } else {
+            throw new IOException('Could not open ' . $filePath . ' for reading.');
+        }
+    }
+
+    /**
+     * Returns an iterator to iterate over sheets.
+     *
+     * @return SheetIterator To iterate over sheets
+     */
+    public function getConcreteSheetIterator()
+    {
+        return $this->sheetIterator;
+    }
+
+    /**
+     * Closes the reader. To be used after reading the file.
+     *
+     * @return void
+     */
+    protected function closeReader()
+    {
+        if ($this->zip) {
+            $this->zip->close();
+        }
+
+        if ($this->sharedStringsHelper) {
+            $this->sharedStringsHelper->cleanup();
+        }
+    }
+}
diff --git a/src/Spout/Reader/XLSX/RowIterator.php b/src/Spout/Reader/XLSX/RowIterator.php
new file mode 100644
index 0000000..6fc1dde
--- /dev/null
+++ b/src/Spout/Reader/XLSX/RowIterator.php
@@ -0,0 +1,369 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX;
+
+use Box\Spout\Common\Exception\IOException;
+use Box\Spout\Reader\IteratorInterface;
+use Box\Spout\Reader\XLSX\Helper\CellHelper;
+
+/**
+ * Class RowIterator
+ *
+ * @package Box\Spout\Reader\XLSX
+ */
+class RowIterator implements IteratorInterface
+{
+    /** Definition of all possible cell types */
+    const CELL_TYPE_INLINE_STRING = 'inlineStr';
+    const CELL_TYPE_STR = 'str';
+    const CELL_TYPE_SHARED_STRING = 's';
+    const CELL_TYPE_BOOLEAN = 'b';
+    const CELL_TYPE_NUMERIC = 'n';
+    const CELL_TYPE_DATE = 'd';
+    const CELL_TYPE_ERROR = 'e';
+
+    /** Definition of XML nodes names used to parse data */
+    const XML_NODE_DIMENSION = 'dimension';
+    const XML_NODE_WORKSHEET = 'worksheet';
+    const XML_NODE_ROW = 'row';
+    const XML_NODE_CELL = 'c';
+    const XML_NODE_VALUE = 'v';
+    const XML_NODE_INLINE_STRING_VALUE = 't';
+
+    /** Definition of XML attributes used to parse data */
+    const XML_ATTRIBUTE_REF = 'ref';
+    const XML_ATTRIBUTE_SPANS = 'spans';
+    const XML_ATTRIBUTE_CELL_INDEX = 'r';
+    const XML_ATTRIBUTE_TYPE = 't';
+
+    /** @var string Path of the XLSX file being read */
+    protected $filePath;
+
+    /** @var string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml */
+    protected $sheetDataXMLFilePath;
+
+    /** @var Helper\SharedStringsHelper Helper to work with shared strings */
+    protected $sharedStringsHelper;
+
+    /** @var \XMLReader The XMLReader object that will help read sheet's XML data */
+    protected $xmlReader;
+
+    /** @var \Box\Spout\Common\Escaper\XLSX Used to unescape XML data */
+    protected $escaper;
+
+    /** @var int Number of read rows */
+    protected $numReadRows = 0;
+
+    /** @var array|null Buffer used to store the row data, while checking if there are more rows to read */
+    protected $rowDataBuffer = null;
+
+    /** @var bool Indicates whether all rows have been read */
+    protected $hasReachedEndOfFile = false;
+
+    /** @var int The number of columns the sheet has (0 meaning undefined) */
+    protected $numColumns = 0;
+
+    /**
+     * @param string $filePath Path of the XLSX file being read
+     * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
+     * @param Helper\SharedStringsHelper $sharedStringsHelper Helper to work with shared strings
+     */
+    public function __construct($filePath, $sheetDataXMLFilePath, $sharedStringsHelper)
+    {
+        $this->filePath = $filePath;
+        $this->sheetDataXMLFilePath = $this->normalizeSheetDataXMLFilePath($sheetDataXMLFilePath);
+        $this->sharedStringsHelper = $sharedStringsHelper;
+
+        $this->xmlReader = new \XMLReader();
+        $this->escaper = new \Box\Spout\Common\Escaper\XLSX();
+    }
+
+    /**
+     * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
+     * @return string Path of the XML file containing the sheet data,
+     *                without the leading slash.
+     */
+    protected function normalizeSheetDataXMLFilePath($sheetDataXMLFilePath)
+    {
+        return ltrim($sheetDataXMLFilePath, '/');
+    }
+
+    /**
+     * Rewind the Iterator to the first element.
+     * Initializes the XMLReader object that reads the associated sheet data.
+     * The XMLReader is configured to be safe from billion laughs attack.
+     * @link http://php.net/manual/en/iterator.rewind.php
+     *
+     * @return void
+     * @throws \Box\Spout\Common\Exception\IOException If the sheet data XML cannot be read
+     */
+    public function rewind()
+    {
+        $this->xmlReader->close();
+
+        $sheetDataFilePath = 'zip://' . $this->filePath . '#' . $this->sheetDataXMLFilePath;
+        if ($this->xmlReader->open($sheetDataFilePath, null, LIBXML_NONET) === false) {
+            throw new IOException('Could not open "' . $this->sheetDataXMLFilePath . '".');
+        }
+
+        $this->numReadRows = 0;
+        $this->rowDataBuffer = null;
+        $this->hasReachedEndOfFile = false;
+        $this->numColumns = 0;
+
+        $this->next();
+    }
+
+    /**
+     * Checks if current position is valid
+     * @link http://php.net/manual/en/iterator.valid.php
+     *
+     * @return boolean
+     */
+    public function valid()
+    {
+        return (!$this->hasReachedEndOfFile);
+    }
+
+    /**
+     * Move forward to next element. Empty rows will be skipped.
+     * @link http://php.net/manual/en/iterator.next.php
+     *
+     * @return void
+     * @throws \Box\Spout\Reader\Exception\SharedStringNotFoundException If a shared string was not found
+     * @throws \Box\Spout\Common\Exception\IOException If unable to read the sheet data XML
+     */
+    public function next()
+    {
+        $isInsideRowTag = false;
+        $rowData = [];
+
+        // Use internal errors to avoid displaying lots of warning messages in case of invalid file
+        // For instance on HHVM, XMLReader->open() won't fail when trying to read a unexisting file within a zip...
+        // But the XMLReader->read() will fail!
+        libxml_clear_errors();
+        libxml_use_internal_errors(true);
+
+        while ($this->xmlReader->read()) {
+            if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === self::XML_NODE_DIMENSION) {
+                // Read dimensions of the sheet
+                $dimensionRef = $this->xmlReader->getAttribute(self::XML_ATTRIBUTE_REF); // returns 'A1:M13' for instance (or 'A1' for empty sheet)
+                if (preg_match('/[A-Z\d]+:([A-Z\d]+)/', $dimensionRef, $matches)) {
+                    $lastCellIndex = $matches[1];
+                    $this->numColumns = CellHelper::getColumnIndexFromCellIndex($lastCellIndex) + 1;
+                }
+
+            } else if ($this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === self::XML_NODE_ROW) {
+                // Start of the row description
+                $isInsideRowTag = true;
+
+                // Read spans info if present
+                $numberOfColumnsForRow = $this->numColumns;
+                $spans = $this->xmlReader->getAttribute(self::XML_ATTRIBUTE_SPANS); // returns '1:5' for instance
+                if ($spans) {
+                    list(, $numberOfColumnsForRow) = explode(':', $spans);
+                    $numberOfColumnsForRow = intval($numberOfColumnsForRow);
+                }
+                $rowData = ($numberOfColumnsForRow !== 0) ? array_fill(0, $numberOfColumnsForRow, '') : [];
+
+            } else if ($isInsideRowTag && $this->xmlReader->nodeType == \XMLReader::ELEMENT && $this->xmlReader->name === self::XML_NODE_CELL) {
+                // Start of a cell description
+                $currentCellIndex = $this->xmlReader->getAttribute(self::XML_ATTRIBUTE_CELL_INDEX);
+                $currentColumnIndex = CellHelper::getColumnIndexFromCellIndex($currentCellIndex);
+
+                $node = $this->xmlReader->expand();
+                $rowData[$currentColumnIndex] = $this->getCellValue($node);
+
+            } else if ($this->xmlReader->nodeType == \XMLReader::END_ELEMENT && $this->xmlReader->name === self::XML_NODE_ROW) {
+                // End of the row description
+                // If needed, we fill the empty cells
+                $rowData = ($this->numColumns !== 0) ? $rowData : CellHelper::fillMissingArrayIndexes($rowData);
+                $this->numReadRows++;
+                break;
+
+            } else if ($this->xmlReader->nodeType == \XMLReader::END_ELEMENT && $this->xmlReader->name === self::XML_NODE_WORKSHEET) {
+                // The closing "</worksheet>" marks the end of the file
+                $this->hasReachedEndOfFile = true;
+            }
+        }
+
+        $readError = libxml_get_last_error();
+        if ($readError !== false) {
+            $readErrorMessage = trim($readError->message);
+            throw new IOException("The {$this->sheetDataXMLFilePath} file cannot be read. [{$readErrorMessage}]");
+        }
+
+        $this->rowDataBuffer = $rowData;
+    }
+
+    /**
+     * Returns the cell's string value from a node's nested value node
+     *
+     * @param \DOMNode $node
+     * @return string The value associated with the cell
+     */
+    protected function getVNodeValue($node)
+    {
+        // for cell types having a "v" tag containing the value.
+        // if not, the returned value should be empty string.
+        $vNode = $node->getElementsByTagName(self::XML_NODE_VALUE)->item(0);
+        if ($vNode !== null) {
+            return $vNode->nodeValue;
+        }
+        return "";
+    }
+
+    /**
+     * Returns the cell String value where string is inline.
+     *
+     * @param \DOMNode $node
+     * @return string The value associated with the cell (null when the cell has an error)
+     */
+    protected function formatInlineStringCellValue($node)
+    {
+        // inline strings are formatted this way:
+        // <c r="A1" t="inlineStr"><is><t>[INLINE_STRING]</t></is></c>
+        $tNode = $node->getElementsByTagName(self::XML_NODE_INLINE_STRING_VALUE)->item(0);
+        $escapedCellValue = trim($tNode->nodeValue);
+        $cellValue = $this->escaper->unescape($escapedCellValue);
+        return $cellValue;
+    }
+
+    /**
+     * Returns the cell String value from shared-strings file using nodeValue index.
+     *
+     * @param string $nodeValue
+     * @return string The value associated with the cell (null when the cell has an error)
+     */
+    protected function formatSharedStringCellValue($nodeValue)
+    {
+        // shared strings are formatted this way:
+        // <c r="A1" t="s"><v>[SHARED_STRING_INDEX]</v></c>
+        $sharedStringIndex = intval($nodeValue);
+        $escapedCellValue = $this->sharedStringsHelper->getStringAtIndex($sharedStringIndex);
+        $cellValue = $this->escaper->unescape($escapedCellValue);
+        return $cellValue;
+    }
+
+    /**
+     * Returns the cell String value, where string is stored in value node.
+     *
+     * @param string $nodeValue
+     * @return string The value associated with the cell (null when the cell has an error)
+     */
+    protected function formatStrCellValue($nodeValue)
+    {
+        $escapedCellValue = trim($nodeValue);
+        $cellValue = $this->escaper->unescape($escapedCellValue);
+        return $cellValue;
+    }
+
+    /**
+     * Returns the cell Numeric value from string of nodeValue.
+     *
+     * @param string $nodeValue
+     * @return int|float The value associated with the cell
+     */
+    protected function formatNumericCellValue($nodeValue)
+    {
+        $cellValue = is_int($nodeValue) ? intval($nodeValue) : floatval($nodeValue);
+        return $cellValue;
+    }
+
+    /**
+     * Returns the cell Boolean value from a specific node's Value.
+     *
+     * @param string $nodeValue
+     * @return bool The value associated with the cell
+     */
+    protected function formatBooleanCellValue($nodeValue)
+    {
+        // !! is similar to boolval()
+        $cellValue = !!$nodeValue;
+        return $cellValue;
+    }
+
+    /**
+     * Returns a cell's PHP Date value, associated to the given stored nodeValue.
+     *
+     * @param string $nodeValue
+     * @return \DateTime|null The value associated with the cell (null when the cell has an error)
+     */
+    protected function formatDateCellValue($nodeValue)
+    {
+        // Mitigate thrown Exception on invalid date-time format (http://php.net/manual/en/datetime.construct.php)
+        try {
+            $cellValue = new \DateTime($nodeValue);
+            return $cellValue;
+        } catch (\Exception $e) {
+            return null;
+        }
+    }
+
+    /**
+     * Returns the (unescaped) correctly marshalled, cell value associated to the given XML node.
+     *
+     * @param \DOMNode $node
+     * @return string|int|float|bool|\DateTime|null The value associated with the cell (null when the cell has an error)
+     */
+    protected function getCellValue($node)
+    {
+        // Default cell type is "n"
+        $cellType = $node->getAttribute(self::XML_ATTRIBUTE_TYPE) ?: self::CELL_TYPE_NUMERIC;
+        $vNodeValue = $this->getVNodeValue($node);
+
+        if (($vNodeValue === '') && ($cellType !== self::CELL_TYPE_INLINE_STRING)) {
+            return $vNodeValue;
+        }
+
+        switch ($cellType) {
+            case self::CELL_TYPE_INLINE_STRING:
+                return $this->formatInlineStringCellValue($node);
+            case self::CELL_TYPE_SHARED_STRING:
+                return $this->formatSharedStringCellValue($vNodeValue);
+            case self::CELL_TYPE_STR:
+                return $this->formatStrCellValue($vNodeValue);
+            case self::CELL_TYPE_BOOLEAN:
+                return $this->formatBooleanCellValue($vNodeValue);
+            case self::CELL_TYPE_NUMERIC:
+                return $this->formatNumericCellValue($vNodeValue);
+            case self::CELL_TYPE_DATE:
+                return $this->formatDateCellValue($vNodeValue);
+            default:
+                return null;
+        }
+    }
+
+    /**
+     * Return the current element, from the buffer.
+     * @link http://php.net/manual/en/iterator.current.php
+     *
+     * @return array|null
+     */
+    public function current()
+    {
+        return $this->rowDataBuffer;
+    }
+
+    /**
+     * Return the key of the current element
+     * @link http://php.net/manual/en/iterator.key.php
+     *
+     * @return int
+     */
+    public function key()
+    {
+        return $this->numReadRows;
+    }
+
+
+    /**
+     * Cleans up what was created to iterate over the object.
+     *
+     * @return void
+     */
+    public function end()
+    {
+        $this->xmlReader->close();
+    }
+}
diff --git a/src/Spout/Reader/Sheet.php b/src/Spout/Reader/XLSX/Sheet.php
similarity index 53%
rename from src/Spout/Reader/Sheet.php
rename to src/Spout/Reader/XLSX/Sheet.php
index c8603ad..9510ecd 100644
--- a/src/Spout/Reader/Sheet.php
+++ b/src/Spout/Reader/XLSX/Sheet.php
@@ -1,15 +1,20 @@
 <?php
 
-namespace Box\Spout\Reader;
+namespace Box\Spout\Reader\XLSX;
+
+use Box\Spout\Reader\SheetInterface;
 
 /**
  * Class Sheet
- * Represents a worksheet within a XLSX file
+ * Represents a sheet within a XLSX file
  *
- * @package Box\Spout\Reader
+ * @package Box\Spout\Reader\XLSX
  */
-class Sheet
+class Sheet implements SheetInterface
 {
+    /** @var RowIterator To iterate over sheet's rows */
+    protected $rowIterator;
+
     /** @var int ID of the sheet */
     protected $id;
 
@@ -20,17 +25,29 @@ class Sheet
     protected $name;
 
     /**
+     * @param string $filePath Path of the XLSX file being read
+     * @param string $sheetDataXMLFilePath Path of the sheet data XML file as in [Content_Types].xml
+     * @param Helper\SharedStringsHelper Helper to work with shared strings
      * @param int $sheetId ID of the sheet
      * @param int $sheetIndex Index of the sheet, based on order of creation (zero-based)
      * @param string $sheetName Name of the sheet
      */
-    function __construct($sheetId, $sheetIndex, $sheetName)
+    public function __construct($filePath, $sheetDataXMLFilePath, $sharedStringsHelper, $sheetId, $sheetIndex, $sheetName)
     {
+        $this->rowIterator = new RowIterator($filePath, $sheetDataXMLFilePath, $sharedStringsHelper);
         $this->id = $sheetId;
         $this->index = $sheetIndex;
         $this->name = $sheetName;
     }
 
+    /**
+     * @return RowIterator
+     */
+    public function getRowIterator()
+    {
+        return $this->rowIterator;
+    }
+
     /**
      * @return int ID of the sheet
      */
diff --git a/src/Spout/Reader/XLSX/SheetIterator.php b/src/Spout/Reader/XLSX/SheetIterator.php
new file mode 100644
index 0000000..aae58c2
--- /dev/null
+++ b/src/Spout/Reader/XLSX/SheetIterator.php
@@ -0,0 +1,112 @@
+<?php
+
+namespace Box\Spout\Reader\XLSX;
+
+use Box\Spout\Reader\IteratorInterface;
+use Box\Spout\Reader\XLSX\Helper\SheetHelper;
+use Box\Spout\Reader\Exception\NoSheetsFoundException;
+
+/**
+ * Class SheetIterator
+ * Iterate over XLSX sheet.
+ *
+ * @package Box\Spout\Reader\XLSX
+ */
+class SheetIterator implements IteratorInterface
+{
+    /** @var Sheet[] The list of sheet present in the file */
+    protected $sheets;
+
+    /** @var int The index of the sheet being read (zero-based) */
+    protected $currentSheetIndex;
+
+    /**
+     * @param string $filePath Path of the file to be read
+     * @param \Box\Spout\Reader\XLSX\Helper\SharedStringsHelper $sharedStringsHelper
+     * @param \Box\Spout\Common\Helper\GlobalFunctionsHelper $globalFunctionsHelper
+     * @throws \Box\Spout\Reader\Exception\NoSheetsFoundException If there are no sheets in the file
+     */
+    public function __construct($filePath, $sharedStringsHelper, $globalFunctionsHelper)
+    {
+        // Fetch all available sheets
+        $sheetHelper = new SheetHelper($filePath, $sharedStringsHelper, $globalFunctionsHelper);
+        $this->sheets = $sheetHelper->getSheets();
+
+        if (count($this->sheets) === 0) {
+            throw new NoSheetsFoundException('The file must contain at least one sheet.');
+        }
+    }
+
+    /**
+     * Rewind the Iterator to the first element
+     * @link http://php.net/manual/en/iterator.rewind.php
+     *
+     * @return void
+     */
+    public function rewind()
+    {
+        $this->currentSheetIndex = 0;
+    }
+
+    /**
+     * Checks if current position is valid
+     * @link http://php.net/manual/en/iterator.valid.php
+     *
+     * @return boolean
+     */
+    public function valid()
+    {
+        return ($this->currentSheetIndex < count($this->sheets));
+    }
+
+    /**
+     * Move forward to next element
+     * @link http://php.net/manual/en/iterator.next.php
+     *
+     * @return void
+     */
+    public function next()
+    {
+        if (array_key_exists($this->currentSheetIndex, $this->sheets)) {
+            $currentSheet = $this->sheets[$this->currentSheetIndex];
+            $currentSheet->getRowIterator()->end();
+
+            $this->currentSheetIndex++;
+        }
+    }
+
+    /**
+     * Return the current element
+     * @link http://php.net/manual/en/iterator.current.php
+     *
+     * @return Sheet
+     */
+    public function current()
+    {
+        return $this->sheets[$this->currentSheetIndex];
+    }
+
+    /**
+     * Return the key of the current element
+     * @link http://php.net/manual/en/iterator.key.php
+     *
+     * @return int
+     */
+    public function key()
+    {
+        return $this->currentSheetIndex + 1;
+    }
+
+    /**
+     * Cleans up what was created to iterate over the object.
+     *
+     * @return void
+     */
+    public function end()
+    {
+        // make sure we are not leaking memory in case the iteration stopped before the end
+        foreach ($this->sheets as $sheet) {
+            $sheet->getRowIterator()->end();
+        }
+    }
+}
diff --git a/src/Spout/Writer/AbstractWriter.php b/src/Spout/Writer/AbstractWriter.php
index 68d452f..e17e16a 100644
--- a/src/Spout/Writer/AbstractWriter.php
+++ b/src/Spout/Writer/AbstractWriter.php
@@ -69,7 +69,7 @@ abstract class AbstractWriter implements WriterInterface
      * By using this method, the data will be written to a file.
      *
      * @param  string $outputFilePath Path of the output file that will contain the data
-     * @return \Box\Spout\Writer\AbstractWriter
+     * @return AbstractWriter
      * @throws \Box\Spout\Common\Exception\IOException If the writer cannot be opened or if the given path is not writable
      */
     public function openToFile($outputFilePath)
@@ -92,7 +92,7 @@ abstract class AbstractWriter implements WriterInterface
      * @codeCoverageIgnore
      *
      * @param  string $outputFileName Name of the output file that will contain the data. If a path is passed in, only the file name will be kept
-     * @return \Box\Spout\Writer\AbstractWriter
+     * @return AbstractWriter
      * @throws \Box\Spout\Common\Exception\IOException If the writer cannot be opened
      */
     public function openToBrowser($outputFileName)
@@ -144,7 +144,7 @@ abstract class AbstractWriter implements WriterInterface
      *                        If empty, no data is added (i.e. not even as a blank row)
      *                        Example: $dataRow = ['data1', 1234, null, '', 'data5', false];
      *
-     * @return \Box\Spout\Writer\AbstractWriter
+     * @return AbstractWriter
      * @throws \Box\Spout\Writer\Exception\WriterNotOpenedException If this function is called before opening the writer
      * @throws \Box\Spout\Common\Exception\IOException If unable to write data
      */
@@ -173,7 +173,7 @@ abstract class AbstractWriter implements WriterInterface
      *                             ['data21', 'data22', null, false],
      *                         ];
      *
-     * @return \Box\Spout\Writer\AbstractWriter
+     * @return AbstractWriter
      * @throws \Box\Spout\Common\Exception\InvalidArgumentException If the input param is not valid
      * @throws \Box\Spout\Writer\Exception\WriterNotOpenedException If this function is called before opening the writer
      * @throws \Box\Spout\Common\Exception\IOException If unable to write data
diff --git a/src/Spout/Writer/CSV.php b/src/Spout/Writer/CSV/Writer.php
similarity index 93%
rename from src/Spout/Writer/CSV.php
rename to src/Spout/Writer/CSV/Writer.php
index 59e37a7..d37ad5b 100644
--- a/src/Spout/Writer/CSV.php
+++ b/src/Spout/Writer/CSV/Writer.php
@@ -1,16 +1,17 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\CSV;
 
+use Box\Spout\Writer\AbstractWriter;
 use Box\Spout\Common\Exception\IOException;
 
 /**
- * Class CSV
+ * Class Writer
  * This class provides support to write data to CSV files
  *
- * @package Box\Spout\Writer
+ * @package Box\Spout\Writer\CSV
  */
-class CSV extends AbstractWriter
+class Writer extends AbstractWriter
 {
     /** Number of rows to write before flushing */
     const FLUSH_THRESHOLD = 500;
@@ -32,7 +33,7 @@ class CSV extends AbstractWriter
      * Sets the field delimiter for the CSV
      *
      * @param string $fieldDelimiter Character that delimits fields
-     * @return CSV
+     * @return Writer
      */
     public function setFieldDelimiter($fieldDelimiter)
     {
@@ -44,7 +45,7 @@ class CSV extends AbstractWriter
      * Sets the field enclosure for the CSV
      *
      * @param string $fieldEnclosure Character that enclose fields
-     * @return CSV
+     * @return Writer
      */
     public function setFieldEnclosure($fieldEnclosure)
     {
diff --git a/src/Spout/Writer/WriterFactory.php b/src/Spout/Writer/WriterFactory.php
index 321f0f1..ee93cd7 100644
--- a/src/Spout/Writer/WriterFactory.php
+++ b/src/Spout/Writer/WriterFactory.php
@@ -19,7 +19,7 @@ class WriterFactory
      * This creates an instance of the appropriate writer, given the type of the file to be read
      *
      * @param  string $writerType Type of the writer to instantiate
-     * @return \Box\Spout\Writer\CSV|\Box\Spout\Writer\XLSX
+     * @return WriterInterface
      * @throws \Box\Spout\Common\Exception\UnsupportedTypeException
      */
     public static function create($writerType)
@@ -28,10 +28,10 @@ class WriterFactory
 
         switch ($writerType) {
             case Type::CSV:
-                $writer = new CSV();
+                $writer = new CSV\Writer();
                 break;
             case Type::XLSX:
-                $writer = new XLSX();
+                $writer = new XLSX\Writer();
                 break;
             default:
                 throw new UnsupportedTypeException('No writers supporting the given type: ' . $writerType);
diff --git a/src/Spout/Writer/WriterInterface.php b/src/Spout/Writer/WriterInterface.php
index 1324053..5bee201 100644
--- a/src/Spout/Writer/WriterInterface.php
+++ b/src/Spout/Writer/WriterInterface.php
@@ -14,7 +14,7 @@ interface WriterInterface
      * By using this method, the data will be written to a file.
      *
      * @param  string $outputFilePath Path of the output file that will contain the data
-     * @return \Box\Spout\Writer\WriterInterface
+     * @return WriterInterface
      * @throws \Box\Spout\Common\Exception\IOException If the writer cannot be opened or if the given path is not writable
      */
     public function openToFile($outputFilePath);
@@ -24,7 +24,7 @@ interface WriterInterface
      * By using this method, the data will be outputted directly to the browser.
      *
      * @param  string $outputFileName Name of the output file that will contain the data. If a path is passed in, only the file name will be kept
-     * @return \Box\Spout\Writer\WriterInterface
+     * @return WriterInterface
      * @throws \Box\Spout\Common\Exception\IOException If the writer cannot be opened
      */
     public function openToBrowser($outputFileName);
@@ -34,7 +34,7 @@ interface WriterInterface
      *
      * @param  array $dataRow Array containing data to be streamed.
      *          Example $dataRow = ['data1', 1234, null, '', 'data5'];
-     * @return \Box\Spout\Writer\WriterInterface
+     * @return WriterInterface
      * @throws \Box\Spout\Writer\Exception\WriterNotOpenedException If the writer has not been opened yetthe writer
      * @throws \Box\Spout\Common\Exception\IOException If unable to write data
      */
@@ -48,7 +48,7 @@ interface WriterInterface
      *              ['data11', 12, , '', 'data13'],
      *              ['data21', 'data22', null],
      *          ];
-     * @return \Box\Spout\Writer\WriterInterface
+     * @return WriterInterface
      * @throws \Box\Spout\Common\Exception\InvalidArgumentException If the input param is not valid
      * @throws \Box\Spout\Writer\Exception\WriterNotOpenedException If the writer has not been opened yet
      * @throws \Box\Spout\Common\Exception\IOException If unable to write data
diff --git a/src/Spout/Writer/Helper/XLSX/CellHelper.php b/src/Spout/Writer/XLSX/Helper/CellHelper.php
similarity index 96%
rename from src/Spout/Writer/Helper/XLSX/CellHelper.php
rename to src/Spout/Writer/XLSX/Helper/CellHelper.php
index 375f953..0f5dc60 100644
--- a/src/Spout/Writer/Helper/XLSX/CellHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/CellHelper.php
@@ -1,12 +1,12 @@
 <?php
 
-namespace Box\Spout\Writer\Helper\XLSX;
+namespace Box\Spout\Writer\XLSX\Helper;
 
 /**
  * Class CellHelper
  * This class provides helper functions when working with cells
  *
- * @package Box\Spout\Writer\Helper\XLSX
+ * @package Box\Spout\Writer\XLSX\Helper
  */
 class CellHelper
 {
diff --git a/src/Spout/Writer/Helper/XLSX/FileSystemHelper.php b/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
similarity index 99%
rename from src/Spout/Writer/Helper/XLSX/FileSystemHelper.php
rename to src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
index fddbb25..f49f8ee 100644
--- a/src/Spout/Writer/Helper/XLSX/FileSystemHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/FileSystemHelper.php
@@ -1,15 +1,15 @@
 <?php
 
-namespace Box\Spout\Writer\Helper\XLSX;
+namespace Box\Spout\Writer\XLSX\Helper;
 
-use Box\Spout\Writer\Internal\XLSX\Worksheet;
+use Box\Spout\Writer\XLSX\Internal\Worksheet;
 
 /**
  * Class FileSystemHelper
  * This class provides helper functions to help with the file system operations
  * like files/folders creation & deletion for XLSX files
  *
- * @package Box\Spout\Writer\Helper\XLSX
+ * @package Box\Spout\Writer\XLSX\Helper
  */
 class FileSystemHelper extends \Box\Spout\Common\Helper\FileSystemHelper
 {
diff --git a/src/Spout/Writer/Helper/XLSX/SharedStringsHelper.php b/src/Spout/Writer/XLSX/Helper/SharedStringsHelper.php
similarity index 95%
rename from src/Spout/Writer/Helper/XLSX/SharedStringsHelper.php
rename to src/Spout/Writer/XLSX/Helper/SharedStringsHelper.php
index 0838306..8a544f9 100644
--- a/src/Spout/Writer/Helper/XLSX/SharedStringsHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/SharedStringsHelper.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Box\Spout\Writer\Helper\XLSX;
+namespace Box\Spout\Writer\XLSX\Helper;
 
 use Box\Spout\Common\Exception\IOException;
 
@@ -8,7 +8,7 @@ use Box\Spout\Common\Exception\IOException;
  * Class SharedStringsHelper
  * This class provides helper functions to write shared strings
  *
- * @package Box\Spout\Writer\Helper\XLSX
+ * @package Box\Spout\Writer\XLSX\Helper
  */
 class SharedStringsHelper
 {
@@ -25,6 +25,9 @@ EOD;
      */
     const DEFAULT_STRINGS_COUNT_PART = 'count="9999999999999" uniqueCount="9999999999999"';
 
+    /** @var resource Pointer to the sharedStrings.xml file */
+    protected $sharedStringsFilePointer;
+
     /** @var int Number of shared strings already written */
     protected $numSharedStrings = 0;
 
diff --git a/src/Spout/Writer/Helper/XLSX/ZipHelper.php b/src/Spout/Writer/XLSX/Helper/ZipHelper.php
similarity index 95%
rename from src/Spout/Writer/Helper/XLSX/ZipHelper.php
rename to src/Spout/Writer/XLSX/Helper/ZipHelper.php
index 429b7a1..4e7c932 100644
--- a/src/Spout/Writer/Helper/XLSX/ZipHelper.php
+++ b/src/Spout/Writer/XLSX/Helper/ZipHelper.php
@@ -1,12 +1,12 @@
 <?php
 
-namespace Box\Spout\Writer\Helper\XLSX;
+namespace Box\Spout\Writer\XLSX\Helper;
 
 /**
  * Class ZipHelper
  * This class provides helper functions to create zip files
  *
- * @package Box\Spout\Writer\Helper\XLSX
+ * @package Box\Spout\Writer\XLSX\Helper
  */
 class ZipHelper
 {
diff --git a/src/Spout/Writer/Internal/XLSX/Workbook.php b/src/Spout/Writer/XLSX/Internal/Workbook.php
similarity index 94%
rename from src/Spout/Writer/Internal/XLSX/Workbook.php
rename to src/Spout/Writer/XLSX/Internal/Workbook.php
index 569d27f..59544b1 100644
--- a/src/Spout/Writer/Internal/XLSX/Workbook.php
+++ b/src/Spout/Writer/XLSX/Internal/Workbook.php
@@ -1,18 +1,18 @@
 <?php
 
-namespace Box\Spout\Writer\Internal\XLSX;
+namespace Box\Spout\Writer\XLSX\Internal;
 
 use Box\Spout\Writer\Exception\SheetNotFoundException;
-use Box\Spout\Writer\Helper\XLSX\FileSystemHelper;
-use Box\Spout\Writer\Helper\XLSX\SharedStringsHelper;
-use Box\Spout\Writer\Sheet;
+use Box\Spout\Writer\XLSX\Helper\FileSystemHelper;
+use Box\Spout\Writer\XLSX\Helper\SharedStringsHelper;
+use Box\Spout\Writer\XLSX\Sheet;
 
 /**
  * Class Book
  * Represents a workbook within a XLSX file.
  * It provides the functions to work with worksheets.
  *
- * @package Box\Spout\Writer\Internal\XLSX
+ * @package Box\Spout\Writer\XLSX\Internal
  */
 class Workbook
 {
@@ -28,10 +28,10 @@ class Workbook
     /** @var bool Whether new sheets should be automatically created when the max rows limit per sheet is reached */
     protected $shouldCreateNewSheetsAutomatically;
 
-    /** @var \Box\Spout\Writer\Helper\XLSX\FileSystemHelper Helper to perform file system operations */
+    /** @var \Box\Spout\Writer\XLSX\Helper\FileSystemHelper Helper to perform file system operations */
     protected $fileSystemHelper;
 
-    /** @var \Box\Spout\Writer\Helper\XLSX\SharedStringsHelper Helper to write shared strings */
+    /** @var \Box\Spout\Writer\XLSX\Helper\SharedStringsHelper Helper to write shared strings */
     protected $sharedStringsHelper;
 
     /** @var Worksheet[] Array containing the workbook's sheets */
@@ -114,7 +114,7 @@ class Workbook
      * Sets the given sheet as the current one. New data will be written to this sheet.
      * The writing will resume where it stopped (i.e. data won't be truncated).
      *
-     * @param \Box\Spout\Writer\Sheet $sheet The "external" sheet to set as current
+     * @param \Box\Spout\Writer\XLSX\Sheet $sheet The "external" sheet to set as current
      * @return void
      * @throws \Box\Spout\Writer\Exception\SheetNotFoundException If the given sheet does not exist in the workbook
      */
@@ -140,7 +140,7 @@ class Workbook
     /**
      * Returns the worksheet associated to the given external sheet.
      *
-     * @param \Box\Spout\Writer\Sheet $sheet
+     * @param \Box\Spout\Writer\XLSX\Sheet $sheet
      * @return Worksheet|null The worksheet associated to the given external sheet or null if not found.
      */
     protected function getWorksheetFromExternalSheet($sheet)
diff --git a/src/Spout/Writer/Internal/XLSX/Worksheet.php b/src/Spout/Writer/XLSX/Internal/Worksheet.php
similarity index 92%
rename from src/Spout/Writer/Internal/XLSX/Worksheet.php
rename to src/Spout/Writer/XLSX/Internal/Worksheet.php
index b403a17..f091004 100644
--- a/src/Spout/Writer/Internal/XLSX/Worksheet.php
+++ b/src/Spout/Writer/XLSX/Internal/Worksheet.php
@@ -1,17 +1,17 @@
 <?php
 
-namespace Box\Spout\Writer\Internal\XLSX;
+namespace Box\Spout\Writer\XLSX\Internal;
 
 use Box\Spout\Common\Exception\InvalidArgumentException;
 use Box\Spout\Common\Exception\IOException;
-use Box\Spout\Writer\Helper\XLSX\CellHelper;
+use Box\Spout\Writer\XLSX\Helper\CellHelper;
 
 /**
  * Class Worksheet
  * Represents a worksheet within a XLSX file. The difference with the Sheet object is
  * that this class provides an interface to write data
  *
- * @package Box\Spout\Writer\Internal\XLSX
+ * @package Box\Spout\Writer\XLSX\Internal
  */
 class Worksheet
 {
@@ -20,13 +20,13 @@ class Worksheet
 <worksheet xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships">
 EOD;
 
-    /** @var \Box\Spout\Writer\Sheet The "external" sheet */
+    /** @var \Box\Spout\Writer\XLSX\Sheet The "external" sheet */
     protected $externalSheet;
 
     /** @var string Path to the XML file that will contain the sheet data */
     protected $worksheetFilePath;
 
-    /** @var \Box\Spout\Writer\Helper\XLSX\SharedStringsHelper Helper to write shared strings */
+    /** @var \Box\Spout\Writer\XLSX\Helper\SharedStringsHelper Helper to write shared strings */
     protected $sharedStringsHelper;
 
     /** @var bool Whether inline or shared strings should be used */
@@ -42,9 +42,9 @@ EOD;
     protected $lastWrittenRowIndex = 0;
 
     /**
-     * @param \Box\Spout\Writer\Sheet $externalSheet The associated "external" sheet
+     * @param \Box\Spout\Writer\XLSX\Sheet $externalSheet The associated "external" sheet
      * @param string $worksheetFilesFolder Temporary folder where the files to create the XLSX will be stored
-     * @param \Box\Spout\Writer\Helper\XLSX\SharedStringsHelper $sharedStringsHelper Helper for shared strings
+     * @param \Box\Spout\Writer\XLSX\Helper\SharedStringsHelper $sharedStringsHelper Helper for shared strings
      * @param bool $shouldUseInlineStrings Whether inline or shared strings should be used
      * @throws \Box\Spout\Common\Exception\IOException If the sheet data file cannot be opened for writing
      */
@@ -76,7 +76,7 @@ EOD;
     }
 
     /**
-     * @return \Box\Spout\Writer\Sheet The "external" sheet
+     * @return \Box\Spout\Writer\XLSX\Sheet The "external" sheet
      */
     public function getExternalSheet()
     {
diff --git a/src/Spout/Writer/Sheet.php b/src/Spout/Writer/XLSX/Sheet.php
similarity index 88%
rename from src/Spout/Writer/Sheet.php
rename to src/Spout/Writer/XLSX/Sheet.php
index 7f8a874..858adcd 100644
--- a/src/Spout/Writer/Sheet.php
+++ b/src/Spout/Writer/XLSX/Sheet.php
@@ -1,12 +1,12 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\XLSX;
 
 /**
  * Class Sheet
  * Represents a worksheet within a XLSX file
  *
- * @package Box\Spout\Writer
+ * @package Box\Spout\Writer\XLSX
  */
 class Sheet
 {
@@ -21,7 +21,7 @@ class Sheet
     /**
      * @param int $sheetIndex Index of the sheet, based on order of creation (zero-based)
      */
-    function __construct($sheetIndex)
+    public function __construct($sheetIndex)
     {
         $this->index = $sheetIndex;
         $this->name = self::DEFAULT_SHEET_NAME_PREFIX . ($sheetIndex + 1);
@@ -45,7 +45,7 @@ class Sheet
 
     /**
      * @param string $name Name of the sheet
-     * @return \Box\Spout\Writer\Sheet
+     * @return Sheet
      */
     public function setName($name)
     {
diff --git a/src/Spout/Writer/XLSX.php b/src/Spout/Writer/XLSX/Writer.php
similarity index 93%
rename from src/Spout/Writer/XLSX.php
rename to src/Spout/Writer/XLSX/Writer.php
index 62e98f1..40f9ae4 100644
--- a/src/Spout/Writer/XLSX.php
+++ b/src/Spout/Writer/XLSX/Writer.php
@@ -1,17 +1,18 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\XLSX;
 
+use Box\Spout\Writer\AbstractWriter;
 use Box\Spout\Writer\Exception\WriterNotOpenedException;
-use Box\Spout\Writer\Internal\XLSX\Workbook;
+use Box\Spout\Writer\XLSX\Internal\Workbook;
 
 /**
- * Class XLSX
+ * Class Writer
  * This class provides base support to write data to XLSX files
  *
- * @package Box\Spout\Writer
+ * @package Box\Spout\Writer\XLSX
  */
-class XLSX extends AbstractWriter
+class Writer extends AbstractWriter
 {
     /** @var string Content-Type value for the header */
     protected static $headerContentType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
@@ -25,7 +26,7 @@ class XLSX extends AbstractWriter
     /** @var bool Whether new sheets should be automatically created when the max rows limit per sheet is reached */
     protected $shouldCreateNewSheetsAutomatically = true;
 
-    /** @var Internal\XLSX\Workbook The workbook for the XLSX file */
+    /** @var Internal\Workbook The workbook for the XLSX file */
     protected $book;
 
     /** @var int */
@@ -33,7 +34,7 @@ class XLSX extends AbstractWriter
 
     /**
      * @param string $tempFolder Temporary folder where the files to create the XLSX will be stored
-     * @return XLSX
+     * @return Writer
      */
     public function setTempFolder($tempFolder)
     {
@@ -45,7 +46,7 @@ class XLSX extends AbstractWriter
      * Use inline string to be more memory efficient. If set to false, it will use shared strings.
      *
      * @param bool $shouldUseInlineStrings Whether inline or shared strings should be used
-     * @return XLSX
+     * @return Writer
      */
     public function setShouldUseInlineStrings($shouldUseInlineStrings)
     {
@@ -55,7 +56,7 @@ class XLSX extends AbstractWriter
 
     /**
      * @param bool $shouldCreateNewSheetsAutomatically Whether new sheets should be automatically created when the max rows limit per sheet is reached
-     * @return XLSX
+     * @return Writer
      */
     public function setShouldCreateNewSheetsAutomatically($shouldCreateNewSheetsAutomatically)
     {
@@ -91,7 +92,7 @@ class XLSX extends AbstractWriter
         $externalSheets = [];
         $worksheets = $this->book->getWorksheets();
 
-        /** @var Internal\XLSX\Worksheet $worksheet */
+        /** @var Internal\Worksheet $worksheet */
         foreach ($worksheets as $worksheet) {
             $externalSheets[] = $worksheet->getExternalSheet();
         }
diff --git a/tests/Spout/Reader/CSVTest.php b/tests/Spout/Reader/CSV/ReaderTest.php
similarity index 70%
rename from tests/Spout/Reader/CSVTest.php
rename to tests/Spout/Reader/CSV/ReaderTest.php
index 8d02849..932633f 100644
--- a/tests/Spout/Reader/CSVTest.php
+++ b/tests/Spout/Reader/CSV/ReaderTest.php
@@ -1,16 +1,17 @@
 <?php
 
-namespace Box\Spout\Reader;
+namespace Box\Spout\Reader\CSV;
 
 use Box\Spout\Common\Type;
+use Box\Spout\Reader\ReaderFactory;
 use Box\Spout\TestUsingResource;
 
 /**
- * Class CSVTest
+ * Class ReaderTest
  *
- * @package Box\Spout\Reader
+ * @package Box\Spout\Reader\CSV
  */
-class CSVTest extends \PHPUnit_Framework_TestCase
+class ReaderTest extends \PHPUnit_Framework_TestCase
 {
     use TestUsingResource;
 
@@ -24,6 +25,16 @@ class CSVTest extends \PHPUnit_Framework_TestCase
         ReaderFactory::create(Type::CSV)->open('/path/to/fake/file.csv');
     }
 
+    /**
+     * @expectedException \Box\Spout\Reader\Exception\ReaderNotOpenedException
+     *
+     * @return void
+     */
+    public function testOpenShouldThrowExceptionIfTryingToReadBeforeOpeningReader()
+    {
+        ReaderFactory::create(Type::CSV)->getSheetIterator();
+    }
+
     /**
      * @expectedException \Box\Spout\Common\Exception\IOException
      *
@@ -44,33 +55,22 @@ class CSVTest extends \PHPUnit_Framework_TestCase
     }
 
     /**
-     * @expectedException \Box\Spout\Reader\Exception\ReaderNotOpenedException
+     * @expectedException \Box\Spout\Common\Exception\IOException
      *
      * @return void
      */
-    public function testReadShouldThrowExceptionIfReadBeforeReaderOpened()
+    public function testOpenShouldThrowExceptionIfCannotOpenFile()
     {
-        $reader = ReaderFactory::create(Type::CSV);
-        $reader->hasNextRow();
-    }
+        $helperStub = $this->getMockBuilder('\Box\Spout\Common\Helper\GlobalFunctionsHelper')
+                        ->setMethods(['fopen'])
+                        ->getMock();
+        $helperStub->method('fopen')->willReturn(false);
 
-    /**
-     * @expectedException \Box\Spout\Reader\Exception\EndOfFileReachedException
-     *
-     * @return void
-     */
-    public function testReadShouldThrowExceptionIfNextRowCalledAfterReadingDone()
-    {
         $resourcePath = $this->getResourcePath('csv_standard.csv');
 
         $reader = ReaderFactory::create(Type::CSV);
+        $reader->setGlobalFunctionsHelper($helperStub);
         $reader->open($resourcePath);
-
-        while ($reader->hasNextRow()) {
-            $reader->nextRow();
-        }
-
-        $reader->nextRow();
     }
 
 
@@ -180,6 +180,50 @@ class CSVTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals($expectedRows, $allRows);
     }
 
+    /**
+     * @return void
+     */
+    public function testReadMultipleTimesShouldRewindReader()
+    {
+        $allRows = [];
+        $resourcePath = $this->getResourcePath('csv_standard.csv');
+
+        $reader = ReaderFactory::create(Type::CSV);
+        $reader->open($resourcePath);
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            // do nothing
+        }
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+        }
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+        }
+
+        $reader->close();
+
+        $expectedRows = [
+            ['csv--11', 'csv--12', 'csv--13'],
+            ['csv--11', 'csv--12', 'csv--13'],
+            ['csv--11', 'csv--12', 'csv--13'],
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * @param string $fileName
      * @param string|void $fieldDelimiter
@@ -197,8 +241,10 @@ class CSVTest extends \PHPUnit_Framework_TestCase
 
         $reader->open($resourcePath);
 
-        while ($reader->hasNextRow()) {
-            $allRows[] = $reader->nextRow();
+        foreach ($reader->getSheetIterator() as $sheetIndex => $sheet) {
+            foreach ($sheet->getRowIterator() as $rowIndex => $row) {
+                $allRows[] = $row;
+            }
         }
 
         $reader->close();
diff --git a/tests/Spout/Reader/Helper/XLSX/CellHelperTest.php b/tests/Spout/Reader/XLSX/Helper/CellHelperTest.php
similarity index 94%
rename from tests/Spout/Reader/Helper/XLSX/CellHelperTest.php
rename to tests/Spout/Reader/XLSX/Helper/CellHelperTest.php
index 8851b33..ff417b9 100644
--- a/tests/Spout/Reader/Helper/XLSX/CellHelperTest.php
+++ b/tests/Spout/Reader/XLSX/Helper/CellHelperTest.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX;
+namespace Box\Spout\Reader\XLSX\Helper;
 
 /**
  * Class CellHelperTest
  *
- * @package Box\Spout\Reader\Helper\XLSX
+ * @package Box\Spout\Reader\XLSX\Helper
  */
 class CellHelperTest extends \PHPUnit_Framework_TestCase
 {
diff --git a/tests/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactoryTest.php b/tests/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactoryTest.php
similarity index 86%
rename from tests/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactoryTest.php
rename to tests/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactoryTest.php
index 18b1c74..ea77b4f 100644
--- a/tests/Spout/Reader/Helper/XLSX/SharedStringsCaching/CachingStrategyFactoryTest.php
+++ b/tests/Spout/Reader/XLSX/Helper/SharedStringsCaching/CachingStrategyFactoryTest.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX\SharedStringsCaching;
+namespace Box\Spout\Reader\XLSX\Helper\SharedStringsCaching;
 
 /**
  * Class CachingStrategyFactoryTest
  *
- * @package Box\Spout\Reader\Helper\XLSX\SharedStringsCaching
+ * @package Box\Spout\Reader\XLSX\Helper\SharedStringsCaching
  */
 class CachingStrategyFactoryTest extends \PHPUnit_Framework_TestCase
 {
@@ -36,18 +36,18 @@ class CachingStrategyFactoryTest extends \PHPUnit_Framework_TestCase
     {
         /** @var CachingStrategyFactory|\PHPUnit_Framework_MockObject_MockObject $factoryStub */
         $factoryStub = $this
-            ->getMockBuilder('\Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyFactory')
+            ->getMockBuilder('\Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyFactory')
             ->disableOriginalConstructor()
             ->setMethods(['getMemoryLimitInKB'])
             ->getMock();
 
         $factoryStub->method('getMemoryLimitInKB')->willReturn($memoryLimitInKB);
 
-        \ReflectionHelper::setStaticValue('\Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyFactory', 'instance', $factoryStub);
+        \ReflectionHelper::setStaticValue('\Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyFactory', 'instance', $factoryStub);
 
         $strategy = $factoryStub->getBestCachingStrategy($sharedStringsUniqueCount, null);
 
-        $fullExpectedStrategyClassName = 'Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\\' . $expectedStrategyClassName;
+        $fullExpectedStrategyClassName = 'Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\\' . $expectedStrategyClassName;
         $this->assertEquals($fullExpectedStrategyClassName, get_class($strategy));
 
         $strategy->clearCache();
@@ -85,7 +85,7 @@ class CachingStrategyFactoryTest extends \PHPUnit_Framework_TestCase
     {
         /** @var CachingStrategyFactory|\PHPUnit_Framework_MockObject_MockObject $factoryStub */
         $factoryStub = $this
-            ->getMockBuilder('\Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyFactory')
+            ->getMockBuilder('\Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyFactory')
             ->disableOriginalConstructor()
             ->setMethods(['getMemoryLimitFromIni'])
             ->getMock();
diff --git a/tests/Spout/Reader/Helper/XLSX/SharedStringsHelperTest.php b/tests/Spout/Reader/XLSX/Helper/SharedStringsHelperTest.php
similarity index 92%
rename from tests/Spout/Reader/Helper/XLSX/SharedStringsHelperTest.php
rename to tests/Spout/Reader/XLSX/Helper/SharedStringsHelperTest.php
index 82631bc..a72d19a 100644
--- a/tests/Spout/Reader/Helper/XLSX/SharedStringsHelperTest.php
+++ b/tests/Spout/Reader/XLSX/Helper/SharedStringsHelperTest.php
@@ -1,16 +1,16 @@
 <?php
 
-namespace Box\Spout\Reader\Helper\XLSX;
+namespace Box\Spout\Reader\XLSX\Helper;
 
-use Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\CachingStrategyFactory;
-use Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\FileBasedStrategy;
-use Box\Spout\Reader\Helper\XLSX\SharedStringsCaching\InMemoryStrategy;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\CachingStrategyFactory;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\FileBasedStrategy;
+use Box\Spout\Reader\XLSX\Helper\SharedStringsCaching\InMemoryStrategy;
 use Box\Spout\TestUsingResource;
 
 /**
  * Class SharedStringsHelperTest
  *
- * @package Box\Spout\Reader\Helper\XLSX
+ * @package Box\Spout\Reader\XLSX\Helper
  */
 class SharedStringsHelperTest extends \PHPUnit_Framework_TestCase
 {
diff --git a/tests/Spout/Reader/XLSXTest.php b/tests/Spout/Reader/XLSX/ReaderTest.php
similarity index 78%
rename from tests/Spout/Reader/XLSXTest.php
rename to tests/Spout/Reader/XLSX/ReaderTest.php
index 531bdb8..0037ca9 100644
--- a/tests/Spout/Reader/XLSXTest.php
+++ b/tests/Spout/Reader/XLSX/ReaderTest.php
@@ -1,17 +1,19 @@
 <?php
 
-namespace Box\Spout\Reader;
+namespace Box\Spout\Reader\XLSX;
 
 use Box\Spout\Common\Exception\IOException;
 use Box\Spout\Common\Type;
+use Box\Spout\Reader\ReaderFactory;
 use Box\Spout\TestUsingResource;
+use Symfony\Component\Config\Definition\Exception\Exception;
 
 /**
- * Class XLSXTest
+ * Class ReaderTest
  *
- * @package Box\Spout\Reader
+ * @package Box\Spout\Reader\XLSX
  */
-class XLSXTest extends \PHPUnit_Framework_TestCase
+class ReaderTest extends \PHPUnit_Framework_TestCase
 {
     use TestUsingResource;
 
@@ -23,6 +25,7 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         return [
             ['/path/to/fake/file.xlsx'],
             ['file_with_no_sheets_in_content_types.xlsx'],
+            ['file_with_sheet_xml_not_matching_content_types.xlsx'],
             ['file_corrupted.xlsx'],
         ];
     }
@@ -36,38 +39,8 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
      */
     public function testReadShouldThrowException($filePath)
     {
-        $this->getAllRowsForFile($filePath);
-    }
-
-    /**
-     * @expectedException \Box\Spout\Reader\Exception\ReaderNotOpenedException
-     *
-     * @return void
-     */
-    public function testHasNextSheetShouldThrowExceptionIfReaderNotOpened()
-    {
-        $reader = ReaderFactory::create(Type::XLSX);
-        $reader->hasNextSheet();
-    }
-
-    /**
-     * @expectedException \Box\Spout\Reader\Exception\EndOfWorksheetsReachedException
-     *
-     * @return void
-     */
-    public function testNextSheetShouldThrowExceptionIfNoMoreSheetsToRead()
-    {
-        $fileName = 'one_sheet_with_shared_strings.xlsx';
-        $resourcePath = $this->getResourcePath($fileName);
-
-        $reader = ReaderFactory::create(Type::XLSX);
-        $reader->open($resourcePath);
-
-        while ($reader->hasNextSheet()) {
-            $reader->nextSheet();
-        }
-
-        $reader->nextSheet();
+        // using @ to prevent warnings/errors from being displayed
+        @$this->getAllRowsForFile($filePath);
     }
 
     /**
@@ -120,6 +93,9 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
      */
     public function testReadShouldSupportAllCellTypes()
     {
+        // make sure dates are always created with the same timezone
+        date_default_timezone_set('UTC');
+
         $allRows = $this->getAllRowsForFile('sheet_with_all_cell_types.xlsx');
 
         $expectedRows = [
@@ -270,7 +246,8 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         $startTime = microtime(true);
 
         try {
-            $this->getAllRowsForFile($fileName);
+            // using @ to prevent warnings/errors from being displayed
+            @$this->getAllRowsForFile($fileName);
             $this->fail('An exception should have been thrown');
         } catch (IOException $exception) {
             $duration = microtime(true) - $startTime;
@@ -305,6 +282,60 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals($expectedRows, $allRows);
     }
 
+    /**
+     * @return void
+     */
+    public function testReadMultipleTimesShouldRewindReader()
+    {
+        $allRows = [];
+        $resourcePath = $this->getResourcePath('two_sheets_with_inline_strings.xlsx');
+
+        $reader = ReaderFactory::create(Type::XLSX);
+        $reader->open($resourcePath);
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            // do nothing
+        }
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            // this loop should only add the first row of the first sheet
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+
+            // this loop should rewind the iterator and restart reading from the 1st row again
+            // therefore, it should only add the first row of the first sheet
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+
+            // not reading any more sheets
+            break;
+        }
+
+        foreach ($reader->getSheetIterator() as $sheet) {
+            // this loop should only add the first row of the current sheet
+            foreach ($sheet->getRowIterator() as $row) {
+                $allRows[] = $row;
+                break;
+            }
+
+            // not breaking, so we keep reading the next sheets
+        }
+
+        $reader->close();
+
+        $expectedRows = [
+            ['s1 - A1', 's1 - B1', 's1 - C1', 's1 - D1', 's1 - E1'],
+            ['s1 - A1', 's1 - B1', 's1 - C1', 's1 - D1', 's1 - E1'],
+            ['s1 - A1', 's1 - B1', 's1 - C1', 's1 - D1', 's1 - E1'],
+            ['s2 - A1', 's2 - B1', 's2 - C1', 's2 - D1', 's2 - E1'],
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * @param string $fileName
      * @return array All the read rows the given file
@@ -317,11 +348,9 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         $reader = ReaderFactory::create(Type::XLSX);
         $reader->open($resourcePath);
 
-        while ($reader->hasNextSheet()) {
-            $reader->nextSheet();
-
-            while ($reader->hasNextRow()) {
-                $allRows[] = $reader->nextRow();
+        foreach ($reader->getSheetIterator() as $sheetIndex => $sheet) {
+            foreach ($sheet->getRowIterator() as $rowIndex => $row) {
+                $allRows[] = $row;
             }
         }
 
diff --git a/tests/Spout/Reader/SheetTest.php b/tests/Spout/Reader/XLSX/SheetTest.php
similarity index 85%
rename from tests/Spout/Reader/SheetTest.php
rename to tests/Spout/Reader/XLSX/SheetTest.php
index 5f6e02d..8f3f9df 100644
--- a/tests/Spout/Reader/SheetTest.php
+++ b/tests/Spout/Reader/XLSX/SheetTest.php
@@ -1,14 +1,15 @@
 <?php
 
-namespace Box\Spout\Reader;
+namespace Box\Spout\Reader\XLSX;
 
 use Box\Spout\Common\Type;
+use Box\Spout\Reader\ReaderFactory;
 use Box\Spout\TestUsingResource;
 
 /**
  * Class SheetTest
  *
- * @package Box\Spout\Reader
+ * @package Box\Spout\Reader\XLSX
  */
 class SheetTest extends \PHPUnit_Framework_TestCase
 {
@@ -41,8 +42,8 @@ class SheetTest extends \PHPUnit_Framework_TestCase
         $reader->open($resourcePath);
 
         $sheets = [];
-        while ($reader->hasNextSheet()) {
-            $sheets[] = $reader->nextSheet();
+        foreach ($reader->getSheetIterator() as $sheet) {
+            $sheets[] = $sheet;
         }
 
         $reader->close();
diff --git a/tests/Spout/Writer/CSVTest.php b/tests/Spout/Writer/CSV/WriterTest.php
similarity index 93%
rename from tests/Spout/Writer/CSVTest.php
rename to tests/Spout/Writer/CSV/WriterTest.php
index ef71b87..83e2e03 100644
--- a/tests/Spout/Writer/CSVTest.php
+++ b/tests/Spout/Writer/CSV/WriterTest.php
@@ -1,16 +1,17 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\CSV;
 
 use Box\Spout\Common\Type;
 use Box\Spout\TestUsingResource;
+use Box\Spout\Writer\WriterFactory;
 
 /**
- * Class CSVTest
+ * Class WriterTest
  *
- * @package Box\Spout\Writer
+ * @package Box\Spout\Writer\CSV
  */
-class CSVTest extends \PHPUnit_Framework_TestCase
+class WriterTest extends \PHPUnit_Framework_TestCase
 {
     use TestUsingResource;
 
@@ -69,7 +70,7 @@ class CSVTest extends \PHPUnit_Framework_TestCase
         ];
         $writtenContent = $this->writeToCsvFileAndReturnWrittenContent($allRows, 'csv_with_utf8_bom.csv');
 
-        $this->assertContains(CSV::UTF8_BOM, $writtenContent, 'The CSV file should contain a UTF-8 BOM');
+        $this->assertContains(Writer::UTF8_BOM, $writtenContent, 'The CSV file should contain a UTF-8 BOM');
     }
 
     /**
@@ -161,6 +162,6 @@ class CSVTest extends \PHPUnit_Framework_TestCase
     private function trimWrittenContent($writtenContent)
     {
         // remove line feeds and UTF-8 BOM
-        return trim($writtenContent, PHP_EOL . CSV::UTF8_BOM);
+        return trim($writtenContent, PHP_EOL . Writer::UTF8_BOM);
     }
 }
diff --git a/tests/Spout/Writer/Helper/XLSX/CellHelperTest.php b/tests/Spout/Writer/XLSX/Helper/CellHelperTest.php
similarity index 97%
rename from tests/Spout/Writer/Helper/XLSX/CellHelperTest.php
rename to tests/Spout/Writer/XLSX/Helper/CellHelperTest.php
index a5045aa..f46b1c6 100644
--- a/tests/Spout/Writer/Helper/XLSX/CellHelperTest.php
+++ b/tests/Spout/Writer/XLSX/Helper/CellHelperTest.php
@@ -1,11 +1,11 @@
 <?php
 
-namespace Box\Spout\Writer\Helper\XLSX;
+namespace Box\Spout\Writer\XLSX\Helper;
 
 /**
  * Class CellHelperTest
  *
- * @package Box\Spout\Writer\Helper\XLSX
+ * @package Box\Spout\Writer\XLSX\Helper
  */
 class CellHelperTest extends \PHPUnit_Framework_TestCase
 {
diff --git a/tests/Spout/Writer/SheetTest.php b/tests/Spout/Writer/XLSX/SheetTest.php
similarity index 94%
rename from tests/Spout/Writer/SheetTest.php
rename to tests/Spout/Writer/XLSX/SheetTest.php
index c9a3e55..d9d6020 100644
--- a/tests/Spout/Writer/SheetTest.php
+++ b/tests/Spout/Writer/XLSX/SheetTest.php
@@ -1,14 +1,15 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\XLSX;
 
 use Box\Spout\Common\Type;
 use Box\Spout\TestUsingResource;
+use Box\Spout\Writer\WriterFactory;
 
 /**
  * Class SheetTest
  *
- * @package Box\Spout\Writer
+ * @package Box\Spout\Writer\XLSX
  */
 class SheetTest extends \PHPUnit_Framework_TestCase
 {
@@ -69,7 +70,7 @@ class SheetTest extends \PHPUnit_Framework_TestCase
         $this->createGeneratedFolderIfNeeded($fileName);
         $resourcePath = $this->getGeneratedResourcePath($fileName);
 
-        /** @var \Box\Spout\Writer\XLSX $writer */
+        /** @var \Box\Spout\Writer\XLSX\Writer $writer */
         $writer = WriterFactory::create(Type::XLSX);
         $writer->openToFile($resourcePath);
 
diff --git a/tests/Spout/Writer/XLSXTest.php b/tests/Spout/Writer/XLSX/WriterTest.php
similarity index 96%
rename from tests/Spout/Writer/XLSXTest.php
rename to tests/Spout/Writer/XLSX/WriterTest.php
index 0abc252..7c6f5ea 100644
--- a/tests/Spout/Writer/XLSXTest.php
+++ b/tests/Spout/Writer/XLSX/WriterTest.php
@@ -1,16 +1,17 @@
 <?php
 
-namespace Box\Spout\Writer;
+namespace Box\Spout\Writer\XLSX;
 
 use Box\Spout\Common\Type;
 use Box\Spout\TestUsingResource;
+use Box\Spout\Writer\WriterFactory;
 
 /**
  * Class XLSXTest
  *
  * @package Box\Spout\Writer
  */
-class XLSXTest extends \PHPUnit_Framework_TestCase
+class WriterTest extends \PHPUnit_Framework_TestCase
 {
     use TestUsingResource;
 
@@ -230,7 +231,7 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         $this->createGeneratedFolderIfNeeded($fileName);
         $resourcePath = $this->getGeneratedResourcePath($fileName);
 
-        /** @var \Box\Spout\Writer\XLSX $writer */
+        /** @var \Box\Spout\Writer\XLSX\Writer $writer */
         $writer = WriterFactory::create(Type::XLSX);
         $writer->setShouldUseInlineStrings(true);
 
@@ -278,7 +279,7 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         ];
 
         // set the maxRowsPerSheet limit to 2
-        \ReflectionHelper::setStaticValue('\Box\Spout\Writer\Internal\XLSX\Workbook', 'maxRowsPerWorksheet', 2);
+        \ReflectionHelper::setStaticValue('\Box\Spout\Writer\XLSX\Internal\Workbook', 'maxRowsPerWorksheet', 2);
 
         $writer = $this->writeToXLSXFile($dataRows, $fileName, true, $shouldCreateSheetsAutomatically = true);
         $this->assertEquals(2, count($writer->getSheets()), '2 sheets should have been created.');
@@ -302,7 +303,7 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
         ];
 
         // set the maxRowsPerSheet limit to 2
-        \ReflectionHelper::setStaticValue('\Box\Spout\Writer\Internal\XLSX\Workbook', 'maxRowsPerWorksheet', 2);
+        \ReflectionHelper::setStaticValue('\Box\Spout\Writer\XLSX\Internal\Workbook', 'maxRowsPerWorksheet', 2);
 
         $writer = $this->writeToXLSXFile($dataRows, $fileName, true, $shouldCreateSheetsAutomatically = false);
         $this->assertEquals(1, count($writer->getSheets()), 'Only 1 sheet should have been created.');
@@ -348,14 +349,14 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
      * @param string $fileName
      * @param bool $shouldUseInlineStrings
      * @param bool $shouldCreateSheetsAutomatically
-     * @return XLSX
+     * @return Writer
      */
     private function writeToXLSXFile($allRows, $fileName, $shouldUseInlineStrings = true, $shouldCreateSheetsAutomatically = true)
     {
         $this->createGeneratedFolderIfNeeded($fileName);
         $resourcePath = $this->getGeneratedResourcePath($fileName);
 
-        /** @var \Box\Spout\Writer\XLSX $writer */
+        /** @var \Box\Spout\Writer\XLSX\Writer $writer */
         $writer = WriterFactory::create(Type::XLSX);
         $writer->setShouldUseInlineStrings($shouldUseInlineStrings);
         $writer->setShouldCreateNewSheetsAutomatically($shouldCreateSheetsAutomatically);
@@ -373,14 +374,14 @@ class XLSXTest extends \PHPUnit_Framework_TestCase
      * @param string $fileName
      * @param bool $shouldUseInlineStrings
      * @param bool $shouldCreateSheetsAutomatically
-     * @return XLSX
+     * @return Writer
      */
     private function writeToMultipleSheetsInXLSXFile($allRows, $numSheets, $fileName, $shouldUseInlineStrings = true, $shouldCreateSheetsAutomatically = true)
     {
         $this->createGeneratedFolderIfNeeded($fileName);
         $resourcePath = $this->getGeneratedResourcePath($fileName);
 
-        /** @var \Box\Spout\Writer\XLSX $writer */
+        /** @var \Box\Spout\Writer\XLSX\Writer $writer */
         $writer = WriterFactory::create(Type::XLSX);
         $writer->setShouldUseInlineStrings($shouldUseInlineStrings);
         $writer->setShouldCreateNewSheetsAutomatically($shouldCreateSheetsAutomatically);
diff --git a/tests/resources/xlsx/file_with_sheet_xml_not_matching_content_types.xlsx b/tests/resources/xlsx/file_with_sheet_xml_not_matching_content_types.xlsx
new file mode 100644
index 0000000..f33c9d7
Binary files /dev/null and b/tests/resources/xlsx/file_with_sheet_xml_not_matching_content_types.xlsx differ