Methods of broadcasting

Historically, there have been several methods used for broadcasting electronic media:

• Telephone broadcasting (1881–1932): the earliest form of electronic broadcasting (not counting data services offered by stock telegraph companies from 1867, if ticker-tapes are excluded from the definition). Telephone broadcasting began with the advent of Théâtrophone ("Theatre Phone") systems, which were telephone-based distribution systems allowing subscribers to listen to live opera and theatre performances over telephone lines, created by French inventor Clément Ader in 1881. Telephone broadcasting also grew to include telephone newspaper services for news and entertainment programming which were introduced in the 1890s, primarily located in large European cities. These telephone-based subscription services were the first examples of electrical/electronic broadcasting and offered a wide variety of programming.^{[citation needed]}
• Radio broadcasting (experimentally from 1906, commercially from 1920); audio signals sent through the air as radio waves from a transmitter, picked up by an antenna and sent to a receiver. Stations can be linked in radio networks to broadcast common radio programs, either in broadcast syndication, simulcast or subchannels.
• Television broadcasting (telecast), experimentally from 1925, commercially from the 1930s: an extension of radio to include video signals.
• 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.
• Direct-broadcast satellite (DBS) (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 or television broadcast programming, or both, with dedicated satellite radio programming. (See also: Satellite television)
• 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 dedicated internet radio–

Economic models

There are several means of providing financial support for continuous broadcasting:

• Commercial broadcasting: selling radio or television advertisements accompanying the programming (the dominant form in the United States as measured by audience numbers)
• Public broadcasting:
  • voluntary membership subscriptions from individual audience members
  • grants from charitable foundations or business entities
• State-sponsored: a higher degree of state involvement than in public broadcasting
  • direct government payments or operation of public broadcasters
  • indirect government payments, such as radio and television license fees collected from receivers
• Volunteer: in-kind donations of time and skills by community radio and community television broadcasters

Broadcasters may rely on a combination of these business models. For example, in the United States, National Public Radio (NPR) and the Public Broadcasting Service (PBS, television) supplement public membership subscriptions and corporate grants with grants from the Corporation for Public Broadcasting (CPB), which is funded by the federal government.
US public broadcasting corporate and charitable grants are generally given in consideration of underwriting spots which differ from commercial advertisements in that they are governed by specific FCC restrictions, which prohibit the advocacy of a product or a "call to action".