JSF stands for Java Server Faces and it is an industry standard and a server side user interface component framework for building component-based user interfaces for web applications. JSF has set of pre-assembled User Interface (UI).
It is event-driven programming model. By that it means that JSF has all necessary code for event handling and component organization. Application programmers can concentrate on application logic rather sending effort on these issues. It has component model that enables third-party components to be added like AJAX.