Video-on-demand refers to a video service where the viewer first selects a video content from a long list of available content and receives the selected video via his subscription channel.
This differs from a linear TV service where a viewer's choice of content is limited to the number of channels he or she subscribes to, with each channel having a fixed line-up of content.
Video-on-demand service can be a standalone service (standalone video-on-demand) or offered as an add-on to a linear TV service.
As a standalone service, subscribers subscribe to a video-on-demand channel and can then watch as many shows as there are in the channel's content library. In this case, the subscriber is typically offered a new selection of content every month in addition to past content archives. Standalone video-on-demand is subscribed on a monthly basis.
As an add-on service, video-on-demand is offered by IPTV, cable TV and satellite TV providers to enable subscribers to purchase a few additional pieces of content on top of their month subscription. This form of video-on-demand is priced on per-content basis.