The radio spectrum is the part of the electromagnetic spectrum from 3 Hz to 3000 GHz (3 THz) allocated to some 40 Radiocommunication services in line to the Radio Regulations (RR) of the International Telecommunication Union (ITU). The transmission, emission and/or reception of radio waves for specific telecommunication purposes of radio waves is strictly regulated by the national administration.
Different parts of the radio spectrum are allocated for different radio transmission technologies and applications. In some cases, parts of the radio spectrum is sold or licensed to operators of private radio transmission services (for example, cellular telephone operators or broadcast television stations). Ranges of allocated frequencies are often referred to by their provisioned use (for example, cellular spectrum or television spectrum).
A band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose.