PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML to produce dynamic web pages. It can be embedded into HTML and generally runs on a web server, which needs to be configured to process PHP code and create web page content from it. It can be deployed on most web servers and on almost every operating system and platform free of charge.[3] PHP is installed on over 20 million websites and 1 million web servers.

PHP was originally created by Rasmus Lerdorf in 1995and has been in continuous development ever since. The main implementation of PHP is now produced by The PHP Group and serves as the de facto standard for PHP as there is no formal specification.PHP is free software released under the PHP License, which is incompatible with the GNU General Public License (GPL) because of restrictions on the use of the term PHP.

For more details about PHP please check this site www.php.net