The PHP development team is proud to announce the immediate availability of PHP 5.5.0. This release includes a large number of new features and bug fixes.

The key features of PHP 5.5.0 include:

Added generators and coroutines.
Added the finally keyword.
Added a simplified password hashing API.
Added support for constant array/string dereferencing.
Added scalar class name resolution via ::class.
Added support for using empty() on the result of function calls and other expressions.
Added support for non-scalar Iterator keys in foreach.
Added support for list() constructs in foreach statements.
Added the Zend OPcache extension for opcode caching.
The GD library has been upgraded to version 2.1 adding new functions and improving existing functionality.
A lot more improvements and fixes.

Changes that affect compatibility:

PHP logo GUIDs have been removed.
Windows XP and 2003 support dropped.
Case insensitivity is no longer locale specific. All case insensitive matching for function, class and constant names is now performed in a locale independent manner according to ASCII rules.

For users upgrading from PHP 5.4, a migration guide is available detailing the changes between 5.4 and 5.5.0.

For a full list of changes in PHP 5.5.0, see the ChangeLog.