In computing, Facelets is an open-source Web template system under the Apache license and the default view handler technology (aka view declaration language) for JavaServer Faces (JSF). The language requires valid input XML documents to work. Facelets supports all of the JSF UI components and focuses completely on building the JSF component tree, reflecting the view for a JSF application.
Although both JSP and JSF technologies have been improved to work better together, Facelets eliminates the issues noted in Hans Bergsten's article "Improving JSF by Dumping JSP"[1]