Cable, for electric and communications use, is an insulated wire or bundle of wires that carry electric current, or a bundle of glass fibers that carry pulses of light. Billions of miles of cable carry communications signals and electric power throughout the world. Millions of feet of specialized cables are used in computers as well as in a wide variety of other electrical and electronic devices. The terms cable and wire are sometimes used interchangeably.
Communications systems that transmit radio signals through the air have begun to replace some cables. In many cases, however, cables still provide the most practical means of transmitting communications signals.
