At the most basic level PHP acts as a filter to preprocess incoming web pages so that calculations and database queries can be performed prior to being viewed by the end user.
According to php.net:
“PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.”
In fact php is used by over 20 million domains worldwide. Although PHP has become associated with the term “Hypertext Preprocessor” it was originally referred to by its author as “Personal Home Page Tools” or PHP Tools for short. Some of the sites using PHP today include: Facebook, Wikipedia, Digg, and WordPress.
