Radio network in the context of "American Broadcasting Company"

Radio broadcasting is the transmission of electromagnetic radiation (radio waves) to receivers over a wide area. Most broadcasts are audio (sound), sometimes with embedded metadata. Listeners require a broadcast radio receiver to receive these signals. "Terrestrial" broadcasts, including AM, FM, and DAB stations, originate from land-based transmitters, whereas "satellite radio" signals originate from a satellite in Earth orbit.

Stations may produce their own programming or be affiliated with a radio network that provides content either through broadcast syndication or by simulcasting, or both. The most common transmission technologies are analog and digital. Analog radio uses one of two modulation methods: amplitude modulation (AM) or frequency modulation (FM). Digital radio stations transmit using one of several digital audio standards, such as DAB (Digital Audio Broadcasting), HD Radio, or DRM (Digital Radio Mondiale).

Terrestrial television, or over-the-air television (OTA) is a type of television broadcasting in which the content is transmitted via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in Canada and the United States it is called over-the-air or simply broadcast. This type of TV broadcast is distinguished from newer technologies, such as satellite television (direct broadcast satellite or DBS television), in which the signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of 64–97 kilometres (40–60 miles), although under better conditions and with tropospheric ducting, signals can sometimes be received hundreds of kilometers distant.

Terrestrial television was the first technology used for television broadcasting. The BBC began broadcasting in 1929 and by 1930 many radio stations had a regular schedule of experimental television programmes. However, these early experimental systems had insufficient picture quality to attract the public, due to their mechanical scan technology, and television did not become widespread until after World War II with the advent of electronic scan television technology. The television broadcasting business followed the model of radio networks, with local television stations in cities and towns affiliated with television networks, either commercial (in the US) or government-controlled (in Europe), which provided content. Television broadcasts were in greyscale (called black and white) until the transition to color television in the 1960s.

A global network is any communication network that spans the entire Earth. The term, as used in this article, refers in a more restricted way to bidirectional communication networks based on technology. Early networks such as international mail and unidirectional communication networks, such as radio and television, are described elsewhere.

The first global network was established using electrical telegraphy and global span was achieved in 1899. The telephony network was the second to achieve global status, in the 1950s. More recently, interconnected IP networks (principally the Internet, with estimated 2.5 billion users worldwide in 2014), and the GSM mobile communication network (with over 6 billion worldwide users in 2014) form the largest global networks of all.

The National Broadcasting Company (NBC) is an American commercial broadcast television and radio network, serving as the flagship property of NBC Entertainment, a division of NBCUniversal, which is a subsidiary of Comcast. It is one of NBCUniversal's two main flagship subsidiaries, alongside Universal Studios. It is the first and oldest major broadcast programming network in the United States.

NBC's headquarters are located in New York City at Rockefeller Center's Comcast Building, the network's longtime home. The network's predecessor parent companies were integral to the center's construction. NBC also notably has offices at the NBC Tower in Chicago, Illinois, and at 10 Universal City Plaza in Los Angeles, California.

CBS Broadcasting Inc., commonly shortened to CBS (an abbreviation of its original name, the Columbia Broadcasting System), is an American commercial broadcast television and radio network and the flagship property of the CBS Entertainment Group division of Paramount Skydance. It is one of Paramount Skydance's three flagship subsidiaries, along with partial namesake Paramount Pictures and MTV.

Founded in 1927, headquartered at the CBS Building in New York City and being part of the "Big Three" television networks, CBS has major production facilities and operations at the CBS Broadcast Center and One Astor Plaza (both also in that city) and Television City and the CBS Studio Center in Los Angeles. It is sometimes referred to as the Eye Network, after the company's trademark symbol of an eye (which has been in use since October 20, 1951), and also the Tiffany Network, which alludes to the perceived high quality of its programming during the tenure of William S. Paley (and can also refer to some of CBS's first demonstrations of color television, which were held in the former Tiffany and Company Building in New York City in 1950).