The Hitchhiker's Guide to the Galaxy is a science fiction comedy series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, and over several years it gradually became an international multi-media phenomenon. Adaptations have included stage shows, a "trilogy" of five books published between 1979 and 1992, a sixth novel penned by Eoin Colfer in 2009, a 1981 TV series, a 1984 computer game, and three series of three-part comic book adaptations of the first three novels published by DC Comics between 1993 and 1996. There were also two series of towels, produced by Beer-Davies, that are considered by some fans to be an "official version" of The Hitchhiker's Guide to the Galaxy, as they include text from the first novel. A Hollywood-funded film version, produced and filmed in the UK, was released in April 2005, and radio adaptations of the third, fourth, and fifth novels were broadcast from 2004 to 2005.
The title is the name of a fictional, eccentric, electronic travel guide, The Hitchhiker's Guide to the Galaxy, prominently featured in the series.
In the series, DON'T PANIC (always upper-case) is a phrase written on the cover of The Hitchhiker's Guide to the Galaxy. The novel explains that this was partly because the device "looked insanely complicated" to operate, and partly to keep intergalactic travelers from panicking. It is said that despite its many glaring (and occasionally fatal) inaccuracies, the Hitchhiker's Guide to the Galaxy itself has outsold the Encyclopedia Galactica because it is slightly cheaper, and because it has the words "DON'T PANIC" in large, friendly letters on the cover.
Arthur C. Clarke said Douglas Adams' use of "Don't panic" was perhaps the best advice that could be given to humanity.