What has changed in PHP 5.4.x when compared to 5.3.x?

What has changed in PHP 5.4.x when compared to 5.3.x? The main differences, updates and advantages,.

If I remember correctly I think traits and closures were introduced in 5.4

PHP 5.4 changes:

http://php.net/manual/en/migration54.changes.php

PHP 5.5 changes:

http://php.net/manual/en/migration55.changes.php