Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. The audience may be the general public or a relatively large sub-audience, such as children or young adults.
There is a wide variety of broadcasting systems, all of which have different capabilities. The smallest broadcasting systems are institutional public address systems, which transmit spoken messages and music within, for example, a school or hospital, and low-powered radio or television stations transmitting programs to a small local area. National radio and television broadcasters have nationwide coverage, using retransmitter towers, satellite systems, and cable distribution. Satellite radio and television broadcasting can cover areas as wide as entire continents, while internet channels can distribute text or streamed music and speech worldwide. Individuals can also use make use of internet services to stream or podcast sound or video.
The sequencing of content in a broadcast is called a schedule. As with all technological endeavors, a number of technical terms and slang have developed. A list of these terms can be found at list of broadcasting terms. Television and radio programs are distributed through radio broadcasting or cable, often both simultaneously. By coding signals and having decoding equipment in homes, the latter also enables subscription-based channels and pay-per-view services.
The term "broadcast" originally referred to the sowing of seeds by scattering them over a wide field. It was adopted by early radio engineers from the midwestern United States to refer to the analogous dissemenation of radio signals. Broadcasting forms a very large segment of the mass media. Broadcasting to a very narrow range of audience is called narrowcasting.
Economically there are a few ways in which stations are able to continually broadcast. Each differs in the method by which stations are funded:
Broadcasters may rely on a combination of these business models. For example, National Public Radio, a non-commercial network within the United States, receives grants from the Corporation for Public Broadcasting (which in turn receives funding from the U.S. government), by public membership, and by selling "extended credits" to corporations.
