This component allows you to render a part of the page to a buffer, and then use the buffer later.
One use of this is the dataScroller. If you display a table with t:dataTable, you can't have dataScroller BEFORE the table, as it can't find the not yet rendered table. So, the solution is that you first render the table to a buffer, then you render the dataScroller, and then you render the buffer's content. That way, the dataScroller will appear before the table even though it was rendered after it.
Note : the generated links within the buffer are only supported with the MyFaces implementation because of the lack of standard dummy form parameters support.