CDN (Content Delivery) is a robust service for the efficient delivery of high volume media-rich content by companies delivering their content over the Internet.  CDN requires carrier-grade systems, software and networks to effectively delivery high demand peaks of traffic for large media events (i.e., SuperBowl, Victoria's Secret,  etc.) that experience spikes in content demand.  CDN is useful on an every day basis for high traffic sites from the biggies like Amazon and Google, to commerical enterprises with high user volumes and large data files.