WordPress is a free and open source blogging product based on PHP and MySQL, and a CMS that runs on a Web hosting service. WordPress is one of the most popular blogging systems due to its rich feature set and enhancements. It comes in two flavours: WordPress.org is an open source CMS that has been created, supported, managed and maintained by a community of passionate developers. WordPress.com is a shared hosting platform that uses WordPress and manages security, updates and backups for its users. As a user, you need not worry about installation with WordPress.com.