See also television, Digital television, Color television, High-definition television (HD)
Analog television (or analogue television), the original television technology, uses analog signals to transmit video and audio. In an analog television broadcast, brightness, color, and sound are represented by the amplitude, phase, and frequency of the signal.
The strength of an analog signal varies over a continuous range of possible values, meaning that electronic noise and interference may be introduced. Thus, a moderately weak signal becomes snowy and subject to interference. In contrast, picture quality from a digital television (DTV) signal remains good until the signal level drops below a certain threshold (the "digital cliff"), where reception is either no longer possible or becomes intermittent.
Analog television may be wireless (as in terrestrial and satellite television) or distributed over a cable network (cable television).
All broadcast television systems traditionally used analog signals. Starting after the year 2000, motivated by the lower bandwidth requirements of compressed digital signals, a digital television transition has been underway in most of the world, with different deadlines for the cessation of analog broadcasts. Countries that still primarily use analogue systems are mostly in Africa, Asia, and South America.