The Viasat channels were launched in June 2008 and also included an on-demand service.

In addition, the channel offers online, interactive and on-demand services which allow opportunities for immediate involvement.

The move is likely to rattle the emerging market for on-demand services and challenge rival music companies to follow Universal's lead.

It will have limited release in select theatres and on-demand services on 1 April 2011.

Because many sites offer on-demand services, you don't have to keep track of scheduling.

In these years, the first on-demand service, the Radiobus, was introduced to operate during the night.

That, in turn, is seen as holding back the market for digital televisions and the on-demand services that might come with them.

In contrast, 4oD channel 4's on-demand service offers many of its television shows that were originally aired years ago.

"At that point news may not be as much of a 24-hour service as an on-demand service."

Share taxi offers on-demand services in many parts of the world and some services will wait until the vehicle is full before it starts.