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HDTV, or high-definition television, means a digital television broadcasting system that stands out for its high resolution in comparison with the traditional – NTSC, SECAM, PAL – system. With enough video compression, digital television requires less bandwidth and thus it is broadcast digitally.

This technology was first introduced in the 1990s by Digital HDTV Grand Alliance - a group of TV firms and MIT. But a demonstration of its qualities was held in the United States in 1981. It had a 5:3 aspect ratio, similar to the Japanese system. In Japan, NHK, the state broadcaster, had first developed consumer HDTV in 1969, with a 5:3 aspect ratio. However, the system was launched only in the late 1990s.

This was preceded by a lot of discussion in the international telecommunication world regarding setting up of a comprehensive HDTV standard. Agreement on the aspect ratio was reached. Because of widescreen cinema, the aspect ratio of 16:9 (1.78) was decided as a compromise between 5:3 (1.67) and the common 1.85 widescreen cinema format.

The then USSR, in 1958, had created Transformer for military purposes. This was the first high-resolution television system that could produce an image of 1,125 lines of resolution. It was designed for TV conferences among military commands.

In the US, on April 6, 1997, CBS set up demos of this technology to evaluate its working. It went on air with WCBS-HD from the top of the Empire State Building. The country then put up the first HDTV sets for sale in 1998.

Europe did not use this technology to develop any established public broadcast service. However, analogue 1,125-line HD-MAC test broadcasts were performed in the early 1990s.

HDTV became affordable for consumer use only after further development of its technology to a level whereby it was possible to deliver sufficient storage capacity and processing power to support compression algorithms. This could happen only because of transition from analogue to digital TV standards. This was in early 2000 and thereafter, it became profitable also for broadcasters and programme makers.

Presently, the HDTV broadcast standards feature ATSC (US) and DVB (Europe and most countries in the world). An additional feature is providing 5.1-channel surround sound audio. This is done with the use of Dolby Digital (AC-3) format.

A transition to digital television features prominently in the future plans of most developed nations. This does not necessarily mean using only HDTV technology. For instance, the US has plans next year to end all full-power terrestrial analogue broadcasting, by allowing both standard definition TV (SDTV) and HDTV.