JavaServer Faces (JSFs) make creating a user interface on the server side modular by incorporating the MVC design pattern in its implementation. It also provides easy-to-use tags for common user interface controls that can save states across multiple request-response exchanges between client and server. For example, if you have a page that posts form data from a browser, you can have a JSF save that data in a Java bean so that it can be used subsequently in the response to the same or different request. JSFs also make it easier to handle UI events on the server side and specify page navigation in an application.

You write the JSF code in JSP, using custom JSP tags created for JSF. JavaServer Faces API 2.3 is part of JEE 8.