WordPress is a popular open-source content management system (CMS) that is widely used for creating and managing websites. It is known for its ease of use, flexibility, and scalability, as well as its extensive plugin and theme ecosystems, which provide users with a wide range of customization options. 

Additionally, WordPress is free to download and use, and has a large and active community of users and developers, making it easy to find support and resources. 

All these factors make it an excellent option for many types of websites, including blogs, portfolios, and online stores.