Already between 1917 and 1920, in the United States, numerous experiments transmitting music and spoken dialogue at a distance were being carried out. In 1920 regular broadcasting began. The first to produce a radio transmission was Pittsburgh's KDKA, a station owned by Westinghouse, leader in consumer electronics retail. In the beginning, broadcasting of the first “programs” (music and brief audio entertainment) was promoted mostly by radio manufacturers and retailers, to trigger a market that was still substantially inexistent. Then, once the radio became more popular, advertising revenue began to finance the new form of communication.

In Europe, regular broadcasting began in the early Twenties, usually under the direct control of the State and in a government monopoly. It was in the United Kingdom where, during the Great War, the technique of broadcasting was most perfected (thanks also to Marconi's active role), and the first national system of radiocommunication established, the British Broadcasting Company, later called the British Broadcasting Corporation or B.B.C. (1922).

In Italy the first experimental broadcasts began in 1924, at first on the initiative of some private companies, then in October of that same year, under conditions of monopoly on public service concession, with the Unione Radiofonica Italiana (URI) progenitor of EIAR (1927-44) and thus of RAI. During the same years in which broadcasting was taking root, the first television (or what was then called) “radiovision” experiments were being carried out in the USA and in the United Kingdom. With the introduction of circular diffusion, not only was a new kind of entertainment beginning to develop, but a completely new model of communication was coming to life.

The practical possibility of transmitting sound via air, or “radio telephony”, is linked to the development of amplification techniques. It was the American inventor Lee De Forest who gave the decisive stimulus in 1906-7 by devising the triode, a vacuum tube capable of amplifying, in a controllable manner, the signal (voltage) detected: it was an improvement of the diode, introduced in 1905 by the English inventor Ambrose Fleming.

De Forest quickly caught on that the principal application for his invention was in the audio field, so much so that he named his most evolved version “Audion”. However, it was the Canadian inventor Reginald Aubrey Fessenden who carried out, always in 1906, the first experiments in radiotelephony, not only with the objective of transmitting sound, as with the Morse code, but to send through the air complete audio signals.

At the root of these developments lies another important invention, the microphone, introduced by Thomas Edison in the early 1880's as an evolution and improvement of communication via telephone. Radio telephony quickly found its place in the fields that were dominated by wireless telegraphy (communication between vehicles in motion, communication in the military) but in no more than a few years it developed into something that even Marconi had not foreseen, broadcasting, in other words the radio as a means of mass communication.

Beginning in the Fifties the triode vacuum tube was progressively substituted with a new instrument for amplification, the transistor, which allowed for the miniaturization of the radio, and made it become portable.