Broadcasting is a method of transmitting radio, Internet or television signals (programs) to a number of recipients ("listeners" or "viewers") that belong to a large group. This group may be the public in general or a relatively large audience within the public in general. Thus an Internet channel may distribute text or music world-wide, while a public address system in (say) a workplace may broadcast very limited ad hoc soundbites to a small population within its range.
Television and radio programs are distributed through radio broadcasting or cable, often both simultaneously. By coding signals and having decoding equipment in the homes, the latter also enables subscription based channels and pay-per-view services.
A broadcasting organisation may broadcast several programs at the same time, through several channels (frequencies), for example BBC 1 and 2. On the other hand, two or more organisations may share a channel and each use it during a fixed part of the day. When broadcasting is done via the Internet the term webcasting is often used.
Broadcasting forms a segment of the mass media.
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There are several dominant business models of broadcasting. 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 subscription; and by selling "extended credits" to corporations.
One can distinguish between recorded and live broadcasts. 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.
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, as in the case of the German dirigible airship Hindenburg 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 American 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.
An intermediate form is a delay of a few seconds, to suppress obscenity and technical failures.