WordPress is an open-source CMS developed by Matt Mullenweg and Mike Little in 2003. It is renowned for its flexibility, extensive plugin ecosystem, and ease of use. WordPress powers over 40% of websites on the internet, making it the most popular CMS available. Its key features include a user-friendly interface, customizable themes, and a robust community of developers. With WordPress, you can create anything from a simple blog to a complex e-commerce site. Its vast library of plugins allows you to add functionality with ease, catering to every need.