Video On Demand (VOD) systems are systems which allow users to select and watch video content over a network as part of an interactive television system. VOD systems are either “streaming”, in which viewing can start as the video streams over the Internet (or other network), or “download”, in which the program is brought in its entirety to a set-top box before viewing starts. All download and some streaming video on demand systems allow the user to pause, fast forward, fast rewind, slow forward, slow rewind, jump to previous/future frame etc. In other words to provide a large subset of VCR functionality.
For streaming systems this requires more effort on the part of the server, and may also require greater network bandwidth. It is possible to put video servers on LANs, in which case they can provide very rapid response to users. Streaming video servers can also serve a wider community via a WAN, in which case the responsiveness may be reduced. Nevertheless, it is possible to provide streaming VOD services over a wide area network. Download VOD services are practical to homes equipped with cable modems or DSL lines.