Scottish physicist James Clerk Maxwell developed the theory that predicted the existence of electromagnetic waves, of which radio waves are an example, in the 1860s. His theory was given practical value when Heinrich Hertz, a German physicist, showed that radio waves could be projected through space and were similar to other electromagnetic radiations that produced light and heat. But it was the Italian inventor Guglielmo Marconi who made radio communication feasible, sending and receiving the first radio signals in 1895. "Wireless" signals were sent across the English Channel in 1899 and across the Atlantic Ocean in 1902.

The first radio transmissions used telegraph keys to modulate the radio signal and add information to the radio wave. Morse code and a variety of other specialized codes were employed, both for military and commercial purposes. But other than for amateur radio enthusiasts, there was little of entertainment until the development of radiotelephony techniques permitting the transmission and reception of audio signals - voices and music - by radio.