A satellite is an object that orbits around a celestial body. Earth is a satellite of the Sun, which is a satellite of the Milky way. Man-made satellites can facilitate telecommunications or serve other functions.
An example of a man-made satellite is a radio relay station that orbits the earth. A complete satellite communications system also includes earth stations that communicate with each other via the satellite. The satellite receives a signal transmitted by an originating earth station and retransmits that signal to the destination earth station(s). Satellites are used to transmit telephone, television and other data signals originated by common carriers, broadcasters and distributors of cable television program material.