Open source software is software in which the source code used to create the program is freely available for the public to view, edit, and redistribute.
PHP is a script language and interpreter that is freely available and used primarily on Linux Web servers. PHP, originally derived from Personal Home Page Tools, now stands for PHP: Hypertext Preprocessor, which the PHP FAQ describes as a "recursive acronym."
Wordpress is a free publishing software and content management system (CMS) that is popular in America. The software is open-source allowing developers to create a wide array of plug-ins, themes and widgets. Wordpress is widely considered easy to use and is the CMS of choice for almost 75 million websites.
Joomla is a free and open-source content management system (CMS) for publishing web content. It is built on a model–view–controller web application framework that can be used independently of the CMS.