PHP extensions are sets of instructions that add functionality to your PHP. Extensions can also be employed to recycle frequently used code. You can place a set of functions into one extension and instruct your projects to utilize the extension. Another use for PHP extensions is to improve efficiency and/or speed. Some processor intensive functions can be better coded as an extension, rather than as straight PHP code.
A list of the PHP extensions included with the Zend Server installation, and extensions added to the php.ini by the user, is displayed on the Configurations | PHP page. Use this page to view the status of all your extensions, to quickly and easily load and unload extensions, and to change directives.