PHP is a server-side scripting language that is used by many developers to develop web applications and websites. It is open source and has a large community of supporters and developers. PHP allows developers to create dynamic websites that respond to user interactions and can retrieve and process data from databases. The scripts can either be embedded in the HTML code of the website or stored as separate files on the server.

A variety of functions and extensions in PHP help developers to create complex web applications. Examples include processing forms and input fields, uploading files, querying databases, using encryption and much more. The scripting language is customisable and can be integrated into various types of websites and applications. PHP is also compatible with many database management systems and other server technologies, so it can be easily integrated into existing infrastructures.