PHP

PHP is a server side scripting language used on the Internet to create dynamic web pages. It is often coupled with MySQL, a relational database server that can store the information and variables the PHP files may use. Together they can create everything from the simplest web site to a full blown business web site, an interactive web forum, or even an online role playing game.

Reference

http://php.about.com/od/learnphp/ss/phpbasics.htm