FOR THOSE of us yet to get to grips with digital, Gavyn Davies called it "the fourth revolution in broadcasting" after radio, black and white television, then colour. Today's TV signals are analogue and work like a continuous wave, but they take up a great deal of the airwaves. The way digital works - by converting sound and pictures into the sort of encoded signals used by computers - takes up less space so you have room for more channels.

With more channels, the viewer can be offered, for instance, 20 starting times for Coronation Street, so being late does not mean missing an episode. You could watch a wildlife channel all evening and play director by selecting the camera angles, or by choosing a replay or close-up. The channels can be used for home shopping or accessing the Internet.

Digital TV can be received using cable, an aerial or satellite dish. A set-top box is needed to decode the digital stream. If you take a box offered free by Sky or ONdigital, you then have to sign up to their subscription boxes. The standard ITV and BBC channels are included free, as are BBC Choice, News 24 and ITV2.

We have about 10 years left before the analogue transmitters are turned off and our televisions become redundant. All future TVs will have in- built digital capability.