WordPress is a free and open-source content management system (CMS) based on PHP and MySQL.
WordPress is reportedly the most popular website management or blogging system in use on the Web, supporting more than 60 million websites.
WordPress was released on May 27, 2003, by its founders, Matt Mullenweg and Mike Little, as a fork of b2/cafelog. WordPress is released under the GPLv2 (or later) license.
Read more: en.wikipedia.org