Although we live in digital world, there is still much legacy analogue equipment in use in video production. We must not forget that the majority of television viewers still watch an analogue transmission, and the changeover to digital reception may not happen until 2010, varying from country to country. The pioneers in digital transmission have been the satellite operators, where the driving force for the deployment of digital transmission (using the MPEG-2 standard) has allowed the emission of four to six times the number of channels within a given transponder bandwidth. Therefore, any overview has to start in the analogue domain.

Essentially television is the reproduction of a moving 2-D image by the transmission of a regular sequence of colour values or samples (in a digital system).Television started as a monochrome system, with colour added later.The colour information was interleaved into the luminance channel without requiring any additional bandwidth. How this was achieved is a pre-cursor to modern compression techniques.

Analogue television uses several techniques to lower the bandwidth requirements without causing unacceptable visual artefacts. Some of these artefacts may today be considered as obvious distortions, but it must be remembered that the engineering compromises were made half a century ago, and were implemented with a handful of vacuum tubes. The methods used include scan interlace, colour space conversion, and chrominance band limiting. This is called composite video.