What is PHP?

PHP (PHP: Hypertext Preprocessor) is a computer scripting language, originally designed for producing dynamic web pages. It is mainly used in server-side scripting, but can be used from a command line interface or in standalone graphical applications. PHP is a widely-used general-purpose scripting language that is especially suited for web development and can be embedded into HTML. It generally runs on a web server, taking PHP code as its input and creating web pages as output. It can be deployed on most web servers and on almost every operating system and platform free of charge. PHP is installed on more than 20 million websites and 1 million servers. (courtesy of Wikipedia)