Broadcasting is the act of transmitting sound or images by radio or television; literally, casting broadly – hence the use of the term “cast” in simulcast. Interestingly, “cast” means to throw something; derived from an old Norse term.
Broadcasting in the way we think of it began with AM radio at the turn of the last century with the spread of vacuum tube radio transmitters and receivers. Before this, all forms of electronic communication (e.g. telegraph) were one-to-one, where the message intended for a single recipient. The word was later adopted for describing the widespread distribution of information by printed materials from it’s origins likely meaning to spread seeds in agriculture.
Over the air broadcasting is usually associated with radio and television, though in recent years both radio and television transmissions have begun to be distributed by cable (cable television). The field of broadcasting includes both government-managed services such as public radio, community radio and public television, and private commercial radio and commercial television.
Transmission of radio and television programs from a radio or television station to home receivers by radio waves is referred to as “over the air” (OTA) or terrestrial broadcasting and in most countries requires a broadcasting license. Transmissions using a wire or cable, like cable television (which also retransmits OTA stations with their consent), are also considered broadcasts, but do not necessarily require a license (though in some countries, a license is required).
In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well.