RichFaces is an open-source framework for building user interfaces in Java web applications. It extends the capabilities of the JavaServer Faces (JSF) technology by providing a set of rich components, such as data tables, trees, and charts, which enhance the user experience. The framework simplifies the development process by offering features like AJAX support, allowing for dynamic content updates without refreshing the entire page. This makes it easier for developers to create interactive and responsive web applications while maintaining a clean separation between the user interface and business logic.