WordPress is a free and open-source CMS written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system, referred to within WordPress as Themes. WordPress was originally created as a blog-publishing system but has evolved to support other types of web content including more traditional mailing lists and forums, media galleries, membership sites, learning management systems (LMS) and online stores. WordPress is used by more than 60 million websites, including 33.6% of the top 10 million websites as of April 2019, WordPress is one of the most popular content management system solutions in use.
Source: Wikipedia