Television images are not only transmitted through the air, carried by radio waves. Another kind of transmission exists that makes use of a coaxial cable, that is to say a type of telephone connection but capable of transforming a much larger amount of information (about ten times more) than a normal telephone wire.

The first cable transmissions were carried out in North America (USA and mostly Canada) around the mid Sixties. Predominantly small local broadcasting stations were transmitting their own programs or retransmitting (capturing them with a powerful antenna) programs that were difficult to receive with a normal antenna.

In the early Seventies, some companies began to use cable to launch pay TV: television via cable began to compete directly with that via air.

Today cable television, that in some cases utilizes transmitting channels which are much more potent than the coaxial cable, like the fiber-optic one (capable of carrying, on a super thin wire, a quantity of information equivalent to several thousand times more than a normal telephone wire), has reached in some countries, among these the USA, a level of diffusion comparable with that of TV via air.

In other countries, Italy included, the development of this channel of communication was slowed down by political and economic decisions made for the most part in the Seventies.