PHP – Pre-Hypertext Processing
PHP is a scripting language that is used to make web pages on the fly. When a Web Server receives a request to a web page, rather than return the contents of a file, it may run a scripted program stored in a PHP file. The computer runs the script in the PHP file and returns the result to the client.

The WordPress CMS is a large PHP program that manages all aspects of the website. Plugins written in PHP extend the WordPress functionality. WooCommerce is an eCommerce solution plugin for WordPress and is also written with PHP.