One advantage that Facelets has over JSP is its templating mechanism. Templates allow us to specify page layout in one place. Then, we can have template clients that use the layout defined in the template. Since most web applications have consistent layout across pages, using templates makes our applications much more maintainable because changes to the layout need to be made in a single place. If at one point we need to change the layout for our pages (for example, add a footer or move a column from the left side of the page to the right side of the page), we only need to change the template and the change is reflected in all the template clients.