Broadcasting is the distribution of audio and video content to a dispersed audience via any audio or visual mass communications medium, but usually one using electromagnetic radiation (radio waves). The receiving parties may include the general public or a relatively large subset thereof. Broadcasting has been used for purposes of private recreation, non-commercial exchange of messages, experimentation, self-training, and emergency communication such as amateur (ham) radio and amateur television (ATV) in addition to commercial purposes like popular radio or TV stations with advertisements.
The term broadcast was first adopted by early radio engineers from the Midwestern United States, treating broadcast sowing as a metaphor for the dispersal inherent in omnidirectional radio signals.Broadcasting is a very large and significant segment of the mass media.
Originally all broadcasting was composed of analog signals using analog transmission techniques and more recently broadcasters have switched to digital signals using digital transmission.
The world's technological capacity to receive information through one-way broadcast networks more than quadrupled during the two decades from 1986 to 2007, from 432 exabytes of (optimally compressed) information, to 1.9 zettabytes. This is the information equivalent of 55 newspapers per person per day in 1986, and 175 newspapers per person per day by 2007.