What is Coax cable? NTSC/ATSC/QAM TV input?

Coaxial cable, or coax, is an electrical cable with an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield.Coaxial cable is used as a transmission line for radio frequency signals, in applications such as feedlines connecting radio transmitters and receivers with their antennas, computer network connections, and distributing cable television signals.