Some updates as of September 2002:
Terrestrial TV in the UK exists in two forms: the long standing analogue service and a newer digital terrestrial
service. This latter carries more channels, although it requires a special adapter, or a digital TV, to view.
In analogue form all channels with the exception of Five are available virtually nationwide with only small pockets of no reception. Five is more limited and covers about 80% of the UK population with many sparsely populated areas uncovered. Digital terrestrial coverage is increasing as new transmitters are opened.
The digital form includes all the channels described in fondue's original writeup on this node (BBC1, BBC2, ITV, Channel 4 and "Five") but also BBC Choice (soon to be renamed BBC3 and retargeted at a "youth" audience); BBC4 (serious cultural programming); BBC Parliament (think a UK version of C-SPAN); BBC News 24 (an all news channel, what else?) ITV2 and some others. It has the capability of carrying subscription channels, but the company operating these (ITV Digital) ceased operation in early 2002 and the service is currently being relaunched as a completely free-to-view service.
All the channels mentioned are also available on Digital Satellite TV without further charge to the viewer (although he or she will have to buy a satellite receiver). So far, satellite has been far more successful at attracting viewers than the digital terrestrial offering.
Only BBC channels are funded by the licence fee. All other channels are supported by spot advertising. Although programme sponsorship exists for terrestrial channels, it is limited in scope being a form of closely linked advertising (typically "bracketing" the programme itself rather than up-front involvement of the sponsor in the creation or editing of the programme. Certain categories of programme (such as news, current affairs and consumer advice) are excluded even from this limited form of sponsorship. Most of the ITV companies have details on their websites: see http://www2.carlton.com/mediasales/sponsorship/intro.jhtml?nav=sponsorship for Carlton's version