Cable television is a system for delivering broadcast programming to viewers by radio frequency (RF) signals transmitted through coaxial cable and through fibre-optic cable. Cable television is contrasted with terrestrial television, wherein the television signal is transmitted over-the-air by radio waves and received by a television antenna; and with satellite television, wherein a communications satellite transmits the television signal over-the-air by way of radio waves which then are received by a satellite dish antenna. A cable channel is television programming transmitted by cable and by satellite television. Alternative terms for a cable channel include non-broadcast channel and programming service, the latter term is used in legal contexts.