| ArrayObject | Class | Implements IteratorAggregate interface | Converts arrays and objects into iterators |
| ArrayIterator | Class | Implements Iterator interface | Used by ArrayObject ; cannot be instantiated directly |
| CachingIterator | Class | Implements Iterator interface | Provides "look ahead by one" capability using hasNext( ) |
| CachingRecursiveIterator | Class | Extends CachingIterator class; implements RecursiveIterator interface | Adds caching support to recursive iterators |
| DirectoryIterator | Class | Implements Iterator interface | An iterator for directory files |
| FilterIterator | Abstract class | Implements Iterator interface | Allows filtering of other iterators using accept( ) method |
| Iterator | Interface | Defines Iterator interface | Implements an iterator |
| IteratorAggregate | Interface | Defines IteratorAggregate interface | Allows classes to control iteration by returning iterator from getIterator( ) method |
| LimitIterator | Class | Implements Iterator interface | Emulates database LIMIT clause |
| ParentIterator | Class | Extends FilterIterator class; implements RecursiveIterator interface | Filters out leaf items, so only parents (items with children) are processed |
| RecursiveDirectoryIterator | Class | Implements RecursiveIterator interface | A recursive iterator for directory files; goes through all subdirectories |
| RecursiveIterator | Interface | Extends Iterator interface | Implements a recursive iterator |
| RecursiveIteratorIterator | Class | Implements Iterator interface | An iterator for classes that implement RecursiveIterator interface |
| SeekableIterator | Interface | Extends Iterator interface | Adds ability to seek( ) within an iterator; used by LimitIterator class |
| SimpleXMLIterator | Class | Implements Iterator interface | An iterator for XML files using SimpleXML functions; only iterates over XML text nodes |
