PHP is a recursive acronym for PHP: Hypertext Preprocessor (according to php.net), although other sources say that acronym original stood for Personal Home Page and still others claim that it stands for either Pre-Hypertext Processing or Parser Hypertext Preprocessor.

In any case, PHP is an open source, server-side, scripting language which can be embedded in HTML by enclosing it in special tags allowing an HTML document to switch back and forth between PHP and HTML. Since the PHP code is processed by the server and eventually resolved or output as HTML then it can work with any web browser. This makes it a versatile and widely used method of creating dynamic web pages with all the functionality of CGI scripting.

A dynamic web page is defined as a page whose output is customised and dependent on user interaction, e.g., a user customised page, a message board, a database lookup and more. The PHP web page file name is saved with a special file extension, typically .php, php4 or phtml which indicates to the server that it contains PHP code which must be processed before sending to the client browser.

PHP support is now a standard in basic paid web hosting packages although in some cases it may require a database like MySQL to perform certain functions.