PHP stands for Personal Home Page tools; the extension .php is generally used to refer to dynamic web content and server-side scripting language. PHP code is interpreted by a web server with a PHP processor module, which generates the resulting web page.
PHP commands can be embedded directly into an HTML source document rather than calling an external file to process data. It has also evolved to include a command-line interface capability and can be used in standalone graphical applications. PHP is free software released under the PHP License. PHP can be deployed on most web servers and also as a standalone shell on almost every operating system and platform, free of charge.