WordPress is a free CMS
WordPress is a free and open-source content management system (CMS) based on PHP and MySQL
WordPress is installed on a web server that is either part of an Internet hosting service or a network host in its own right. The first case may be a service like WordPress.com, for example, and the second case could be a computer running the software package WordPress.org. A local computer may be used for single-user testing and learning purposes. Features include a plugin architecture and a template system. WordPress was used by more than 26.4% of the top 10 million websites as of April 2016. WordPress is reportedly the easiest and 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 from the Free Software Foundation.