The range of frequencies within the electromagnetic spectrum, above the audio range and below visible light, that can be used to transmit voice, video and data, that is, 3kHz to 300GHz (it is measured in Hertz). Radio spectrum is a valuable resource which is limited in supply, highly sought-after and essential to modern economies. The Office of Communications (Ofcom) manages the UK radio spectrum allocation and has a duty to ensure it is used in the most effective way.