A set of devices to transmit moving pictures and sound over a distance. In daily use is also used to refer to organizations engaged in the production and distribution of television programs. Along with broadcasting is the most widespread means of disseminating information (political, cultural, scientific and cognitive or learning) as well as one of the main means of communication.

TV is based on the principle of the serial elements  Image via radio or by wire. Decomposition of the image on the elements is done by Nipkow disk, a cathode ray tube or a semiconductor matrix. Dot number is selected according to the radio channel bandwidth and physiological criteria. To narrow band of frequencies transmitted and reduce flickering TV screen used interlaced. It also increases the fluidity of motion.

TV tract in general includes the following devices :

TV transmitting camera. Used to convert the image produced by the lens on the target camera tube or semiconductor matrix, the television video signal.
VCR. Records and plays back at the right time video.
Switcher. Allows you to switch between multiple sources of images: cameras, video recorders and others.
Transmitter. Radio frequency signal modulated by a television video signal and transmitted by radio or wire.
Receiver — the TV. With the clock contained in the video signal, the TV picture is displayed on the receiver’s screen (CRT, LCD, plasma).

In addition, to create a TV program using the audio path, the same path broadcast. Sound is transmitted on a separate frequency usually with frequency modulation technology, similar to FM-radio stations. In digital television sound, often multi-channel, is transmitted in the general flow of the image data.