The following are new extensions added (by default) as of PHP 5.2.0:
Filter - validates and filters data, and is designed for use with insecure data such as user input. This extension is enabled by default; the default mode RAW does not impact input data in any way.
JSON - implements the JavaScript Object Notation (JSON) data interchange format. This extension is enabled by default.
Zip - enables you to transparently read or write ZIP compressed archives and the files inside them.