In telecommunications, broadband or high speed is the wide-bandwidth data transmission that uses signals at a wide spread of frequencies or several different simultaneous frequencies. It is used in fast Internet access where the transmission medium can be coaxial cable, optical fiber, wireless Internet (radio), twisted pair cable, or satellite.
Originally used to mean "using a wide-spread frequency" and for services that were analog at the lowest level, in the context of Internet access, "broadband" is now often used to mean any high-speed Internet access that is seemingly always "on" and is faster than dial-up access over traditional analog or ISDN PSTN services.