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 27.5% of the top 10 million websites as of February 2017. WordPress is reportedly the most popular website management or blogging system in use on the Web, supporting more than 60 million websites.
The CMS was released on May 27, 2003 as a fork of b2/cafelog. b2/cafelog was estimated to have been installed on approximately 2,000 blogs as of May 2003. It was written in PHP for use with MySQL by Michel Valdrighi, who is now a contributing developer to WordPress.
As of February 2017, WordPress is used by 58.7% of all the websites whose content management system is known. This is 27.5% of the top 10 million websites.
Visit the WordPress.org website for more information.