Php.definition
PHP (stands for "PHP: Hypertext Preprocessor". It is widely used in webapplications. Many Wikis, including this place, have been written in PHP.
Mostly run as Apache Webserver module, and according to statistics its most likely hosted on The Linux Operating System. While early versions of PHP where clumsy, in its latest incarnation - PHP 5 sports most features of a modern object oriented programming language.