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Radio program formats differ by country, regulation and markets. For instance, the U.S. Federal Communications Commission designates the 88–92 megahertz band in the U.S. for non-profit or educational programming, with advertising prohibited.

See Shortwave for the differences between shortwave, medium wave and long wave spectra. Used largely for international broadcasts by organs of state propaganda, religious organizations, militaries and others.

Radio broadcasting is an audio (sound) broadcasting service, broadcast through the air as radio waves (a form of electromagnetic radiation) from a transmitter to an antenna and a thus to a receiving device. Stations can be linked in radio networks to broadcast common programming, either in syndication or simulcast or both. Audio broadcasting also can be done via cable FM, local wire networks, satellite and the Internet.

AM stations were the earliest broadcasting stations to be developed. AM refers to amplitude modulation, a mode of broadcasting radio waves by varying the amplitude of the carrier signal in response to the amplitude of the signal to be transmitted.

FM refers to frequency modulation, and occurs on VHF airwaves in the frequency range of 88 to 108 MHz everywhere (except Japan and Russia). Japan uses the 76 to 90 MHz band. Russia has two bands widely used by the Soviet Union, 65.9 to 74 MHz and 87.5 to 108 MHz worldwide standard. FM stations are much more popular in economically developed regions, such as Europe and the United States, especially since higher sound fidelity and stereo broadcasting became common in this format.

Many countries outside of the U.S. use a similar frequency band for AM transmissions. Europe also uses the long wave band. In response to the growing popularity of FM radio stereo radio stations in the late 1980s and early 1990s, some North American stations began broadcasting in AM stereo, though this never gained popularity, and very few receivers were ever sold.

Although now being eclipsed by internet-distributed radio, there are many stations that broadcast on shortwave bands using AM technology that can be received over thousands of miles (especially at night). For example, the BBC has a full schedule transmitted via shortwave. These broadcasts are very sensitive to atmospheric conditions and solar activity.

The best known type of radiostation are the ones that broadcast via radiowaves. These include foremost AM and FM stations. There are several subtypes, namely commercial, public and nonprofit varieties as well as student-run campus radio stations and hospital radio stations can be found throughout the developed world.

Also, many other non-broadcast types of radio stations exist. These include base stations for police, fire and ambulance networks, military base stations, dispatch base stations for taxis, trucks, and couriers, emergency broadcast systems, and amateur radio stations.

Satellite radiobroadcasters are slowly emerging, but the enormous entry costs of space-based satellite transmitters, and restrictions on available radio spectrum licenses has restricted growth of this market. In the USA and Canada, just two services, XM Satellite Radio and Sirius Satellite Radio exist. Both XM and Sirius are owned by Sirius XM Radio, which was formed by the merger of XM and Sirius on July 29, 2008, whereas in Canada, XM Radio Canada and Sirius Canada remain separate companies.