Hypertext preprocessor (PHP) is a programming language used to fundamentally enhance HTML in Web pages. It is often used with the open-source relational database management system MySQL in the creation of databases, but has other uses.
PHP is embedded within HTML code to perform certain functions. For example, PHP can be added to HTML in order to perform calculations, or to collect user data. Examples of PHP code that perform calculations include math websites with functionality, including metric conversions. PHP also allows users to perform functions on a website such as posting on a forum or adding information to an address book.
PHP is also capable of editing simple graphics and creating new graphics, when used in conjunction with GD Library. PHP technology is often used to create CAPTCHAs on sites that seek to verify that a human is accessing information as opposed to an automated system.