What is the history of the radio industry?

Google history of radio. There's a massive amount of information out there on the topic -- quite interesting, very extensive, beginning with the role of Marconi, the person largely responsible for the first radio broadcasts,

I would reccomend Scnnel & Cardiff for British broadcasting history, as the British studied the American model it covers the American development as well - it is quite a fascinting subject, Wikipedia has quite a thorough entry basically transmission from around 1906 and commercial 1920The British system differed from the US initially as in Britain a licence was required to receive transmission and in US a licence was needed to transmit. David Sarnoff is probably the most important name you need to start your research, not a simple subject really.