JSF (JavaServer Faces) is a technology that aims to simplify building user interfaces for web applications. The JSF specification has been developed through the Java Community Process under JSR-127. JSF provides developers a powerful API to build reusable User Interface components, connect these components to application data sources and wire client-generated events to server-side event handlers. To learn more about JSF, visit:

• JavaServer Faces Technology: Sun's homepage, the definitive source of information for everything related to JSF.
• A first look at JavaServer Faces: an interesting article introducing basic JavaServer Faces concepts.