Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all aspects of television programming and transmission as well. A semi-mechanical analog television system was first demonstrated in February 1924 by John Logie Baird and moving pictures by Baird on October 30, 1925. A fully electronic system was demonstrated by Philo Taylor Farnsworth in the autumn of 1927. The first analogue service was WGY, Schenectady, New York inaugurated on May 11, 1928.
The earliest television sets were radios with the addition of a television device consisting of a neon tube with a mechanically spinning disk (called a Nipkow disk) that produced a red postage-stamp size image. The first electronic high definition service was in Germany in March 1935, but was only available in 22 public viewing rooms. One of the first major broadcasts involved the 1936 Berlin Olympics. Television usage skyrocketed after World War II with war-related technological advances and additional disposable income. (1930s TV receivers cost the equivalent of $7000 today (2001) and had little available programming.) Color television became available in 1953, backed by the CBS network. The government approved the color broadcast system proposed by CBS, but when RCA came up with a system that did not require changes to the old black and white TV sets, CBS dropped their own proposal and used the new one.
Television in its original and still most popular form involves sending moving images and sound over radio waves, which are received by a receiver (a television). In this sense, it is an extension of radio.
Starting in the 2000s, modern television sets diverged into three different trends:
- standalone TV sets;
- integrated systems with DVD players and/or VHS VCR built into the TV set itself (mostly for small size TV with up to 17" screen, the main idea is to have a complete portable system);
- component systems with separate big screen video monitor, tuner, audio system which the owner connects the pieces together as a high-end home theater system. This approach appeals to videophiles who prefer components which can be upgraded separately.
There are many kinds of video monitors used in modern TV sets. There are CRTs for up to 40" diagonally. Most big screen TVs (upto over 100") use projection technology. Three types of projection systems are used in projection TVs: CRT based, LCD based and reflective imaging chip based. Modern advances brought flat screens to TV that use active matrix LCD or plasma display technology. Flat panel big screen TVs are only 4" thick and can be hung on the wall like a picture. They are extremely attractive and space-saving but they remain extremely expensive.
There are various kinds of television broadcast systems:
- Terrestial television
- Satellite television using standard digital signaling
- Cable television
- both analog and digital systems are available.
- New developments: Digital television (DTV) -- High Definition TV (HDTV) -- Pay-per-view -- Web tv -- programming on-demand.
Programming is broadcast on television stations (sometimes called channels) that are often targeted towards a certain audience. There are many news, sports and film stations and stations such as the MTV and BBC networks are seen throughout many countries.
In the US, TV networks produce prime-time programs for their affiliate stations to air between 7pm and 10pm. Most stations have their own programming off the prime time.