A wide variety of multimedia coding and representation standards have emerged during the past years, in the quest to establish a common denominator for both the research community and the related industry to incorporate results and algorithms in commercial products. MPEG-4 aims to improve where past standards proved ineffective or isolated and integrate different modalities to supply different forms of material, suitable for diverse applications and devices. In this paper, we describe the general concepts that MPEG-4 builds upon and how they are related to multi-user interactive environments and gaming.