PHP is a popular scripting language that is designed to create dynamic web pages (e.g. login pages, shopping carts). The PHP code is embedded into the HTML source of a website and it is run on the web hosting server, rather than on the browser. So, if you check the source code of a PHP web page, it is just plain HTML. Since PHP is a universal scripting language, websites created with PHP are also fully compatible with most of the mobile devices like Android, iPhone, and iPad etc. A large number popular websites, including Facebook and Wikipedia, are written in PHP.

WordPress, Drupal, and Joomla are the most commonly-used open source Content Management Systems(CMS) written in PHP. A lot of webmasters choose these three platforms to build their websites because of their flexibility. There are a lot of themes and plugins created for these three platforms and webmasters can create professional looking websites based on these systems with just a few clicks. Also, their themes are customizable, so webmasters can change the coding to fit their needs.