A television station is a type of radio station that broadcasts both audio and video to television receivers in a particular area. Traditionally, TV stations made their broadcasts by sending specially-encoded radio signals over the air, called terrestrial television. Individual television stations are usually granted licenses by a government agency to use a particular section of the radio spectrum (a channel) through which they send their signals. Some stations use LPTV broadcast translators to retransmit to further areas.
Television stations are now in the process of converting from analogue (NTSC, PAL, or SECAM) to digital (ATSC, DVB or ISDB). In some countries, this is being forced on consumers and stations, while in others it is entirely voluntary.
The term television channel has become synonymous with "TV station" and even television network, leading to confusion. Television stations, in the United States, usually just have one transmitter (or, more recently, two transmitters if the station broadcasts a digital signal in addition to its standard analog signal). In other countries, television stations are also generally associated with a nationwide television network, through which they get significant amounts of programming. Because some regions have had difficulty picking up over-the-air signals (particularly in mountainous areas), direct-to-home satellite and cable television has been introduced. Television channels specifically built to run on cable or satellite blur the line between TV station and TV network. That fact led some early cable networks to call themselves superstations.
In the United States, each nationwide terrestrial broadcast network can have a few "O & O's", stations it owns and operates, usually in the larger broadcast markets. Satellite and cable have created changes. Broadcast stations in an area can sign up to be carried on cable (called "must-carry" in the U.S.), but content providers like TLC Network can too. They aren't licensed to run broadcast equipment like a station and they don't regularly provide content to licensed broadcasters either. Furthermore, a distributor like TNT may begin producing its own programming, and shows presented exclusively on cable by one distributor may be syndicated to broadcast stations.
A person viewing by cable or satellite may not know what kind of organization is responsible for the program, especially if it is syndicated, so what seems to be a station or a network may be neither.
See lists of television channels, for lists by country and language.