WordPress is a free and open-source content management system (CMS) based on PHP and MySQL. To function, WordPress has to be installed on a web server, which would either be part of an Internet hosting service or a network host in its own right. 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 29.4% of the top 10 million websites as of January 2018.
WordPress is an open source community project where tens of thousands of talented people have made contributions to make it into a great software that it is today. There is a core team of developers that lead the project development, but anyone can contribute patches, report bugs, suggest features etc. Furthermore, project leaders change from one version to another. If you get involved into the community, then you can easily become a core contributor of WordPress.