Radio

I'd sit alone and watch your light
My only friend through teenage nights
And ev'rything I had to know
I heard it on my radio

— Queen, "Radio Ga Ga"

The Ur-Example of broadcast media; like Television but without the pictures. You young 'uns might think of it as like a podcast, but sent over the open airwaves. As a serial broadcast medium, radio shares many tropes with television. Indeed, early radio originated many of these tropes. Several television series originated on the wireless. These days, of course, television has eclipsed radio to the extent the latter is seen as mostly a format for music and live talk shows, though some stations in some countries (like BBC Radio 4 in the UK and CBC Radio One in Canada) offer drama, comedy, documentaries and more.

The name "radio" comes from the low-energy electromagnetic waves first detected by Heinrich Hertz in 1887. These waves "radiated" out from the spark-gap generator that produced them. The first radio transmitters could only broadcast Morse code, but soon the technology was developed to piggyback audio signals onto a radio-frequency carrier wave. Soon afterward, rules were established to allow for specific radio frequency bands to be allocated to different licensed broadcasters within an area. Eventually, the technology to encode video signals onto radio carrier waves was developed, but by that time radio waves had been used for audio-only broadcasts for so long that the word "radio" had become synonymous with them. (The broadcasters who used radio waves for video signals had to invent a new word for it.) Today, some things called radio, such as cable radio and internet radio stations, don't even use radio waves at all.

See also: Audio Play, Podcast, and Web Original.