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.

The sequencing of content in a broadcast is called a schedule. As with all technological endeavours, 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 dissemination of radio signals. Broadcasting forms a very large segment of the mass media. Broadcasting to a very narrow range of audience is called narrowcasting.

Forms of electronic broadcasting

Historically, there have been several different types of electronic broadcasting mediums:

• Telephone broadcasting (1890–1932): the earliest form of electronic broadcasting, not counting the data services offered by stock telegraph companies from 1867, if ticker-tape machines are excluded from broadcasting's popular definition. Telephone broadcasting began with the advent of telephone newspaper services for news and entertainment programming which were introduced in the 1890s and primarily located in large European cities. These telephone-based systems were the first example of electronic broadcasting and offered a wide variety of programming.

• Radio broadcasting (experimentally from 1906, commercially from 1920): radio broadcasting is an audio (sound) broadcasting service, broadcast through the air as radio waves from a transmitter to an antenna and, thus, to a receiving device. Stations can be linked in radio networks to broadcast common programming, either in syndication or simulcast or both.

• Television broadcasting (experimentally from 1925, commercially from the 1930s): this video-programming medium was long-awaited by the general public and rapidly rose to compete with its older radio-broadcasting sibling.

• Cable radio (also called "cable FM", from 1928) and cable television (from 1932): both via coaxial cable, serving principally as transmission mediums for programming produced at either radio or television stations, with limited production of cable-dedicated programming.

• Satellite television (from circa 1974) and satellite radio (from circa 1990): meant for direct-to-home broadcast programming (as opposed to studio network uplinks and downlinks), provides a mix of traditional radio and/or television broadcast programming with satellite-dedicated programming.

• Webcasting of video/television (from circa 1993) and audio/radio (from circa 1994) streams: offers a mix of traditional radio and television station broadcast programming with internet-dedicated webcast programming.

Economic models

Economically there are a few ways in which stations are able to broadcast continually. Each differs in the method by which stations are funded:

• in-kind donations of time and skills by volunteers (common with community broadcasters)

• direct government payments or operation of public broadcasters

• indirect government payments, such as radio and television licenses

• grants from foundations or business entities

• selling advertising or sponsorships

• public subscription or membership

Broadcasters may rely on a combination of these business models. For example, National Public Radio, a non-commercial network within the U.S., 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.

Recorded broadcasts and live broadcasts

The first regular television broadcasts began in 1937. Broadcasts can be classified as "recorded" or "live". The former allows correcting errors, and removing superfluous or undesired material, rearranging it, applying slow-motion and repetitions, and other techniques to enhance the program. However, some live events like sports telecasts can include some of the aspects including slow-motion clips of important goals/hits, etc., in between the live telecast.

American radio-network broadcasters habitually forbade prerecorded broadcasts in the 1930s and 1940s requiring radio programs played for the Eastern and Central time zones to be repeated three hours later for the Pacific time zone. This restriction was dropped for special occasions, as in the case of the German dirigible airship Hindenburg disaster at Lakehurst, New Jersey, in 1937. During World War II, prerecorded broadcasts from war correspondents were allowed on U.S. radio. In addition, American radio programs were recorded for playback by Armed Forces Radio stations around the world.

A disadvantage of recording first is that the public may know the outcome of an event from another source, which may be a "spoiler". In addition, prerecording prevents live announcers from deviating from an officially approved script, as occurred with propaganda broadcasts from Germany in the 1940s and with Radio Moscow in the 1980s.

Many events are advertised as being live, although they are often "recorded live" (sometimes called "live-to-tape"). This is particularly true of performances of musical artists on radio when they visit for an in-studio concert performance. Similar situations have occurred in television ("The Cosby Show is recorded in front of a live studio audience") and news broadcasting.

A broadcast may be distributed through several physical means. If coming directly from the studio at a single radio or television station, it is simply sent through the air chain to the transmitter and thence from the antenna on the tower out to the world. Programming may also come through a communications satellite, played either live or recorded for later transmission. Networks of stations may simulcast the same programming at the same time, originally via microwave link, now usually by satellite.

Distribution to stations or networks may also be through physical media, such as analog or digital videotape, compact disc, DVD, and sometimes other formats. Usually these are included in another broadcast, such as when electronic news gathering returns a story to the station for inclusion on a news programme.

The final leg of broadcast distribution is how the signal gets to the listener or viewer. It may come over the air as with a radio station or television station to an antenna and receiver, or may come through cable television or cable radio (or "wireless cable") via the station or directly from a network. The Internet may also bring either radio or television to the recipient, especially with multicasting allowing the signal and bandwidth to be shared.

The term "broadcast network" is often used to distinguish networks that broadcast an over-the-air television signal that can be received using a television antenna from so-called networks that are broadcast only via cable or satellite television. The term "broadcast television" can refer to the programming of such networks.
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Legal definitions

United Kingdom

The Copyright, Designs and Patents Act of 1988 defines a broadcast as "a transmission by wireless telegraphy of visual images, sounds, or other information which is capable of lawful reception by the public or which is made for presentation to the public". Thus, it covers radio, television, teletext and telephones.

See also

• 1worldspace – world's first commercial satellite radio direct-to-home broadcaster

• Broadcast television systems – contains the standards of the topic

• Broadcast safe

• Broadcast license

• Broadcasting network

• Broadcast quality

• Cablecast

• Dead air

• European Broadcasting Union (EBU)

• History of broadcasting

• Internet radio

• Internet television

• List of broadcast satellites

• NaSTA

• Nonbroadcast Multiple Access Network (NBMA)

• North American broadcast television frequencies

• Outside broadcast

• Radio Act of 1927

• Reality television

• Society of Broadcast Engineers (SBE)

• Streaming media

• Television studio

• Television broadcasting in Australia

• Webcast