In this chapter, the scene description format specified in MPEG-4 Systems [MPEG4-1] has been presented. After introducing the basic concepts, a set of scenes of increasing complexity served as the basis for presenting the different kinds of nodes and their features. Important new BIFS features, currently being finalized, were previewed. Finally, a reference section gathers a short but exhaustive description of all BIFS nodes. For another view on BIFS, see [Sign99] or Chapter 14 of [PuCh00].