The first radio series comes from a proposal called "The Ends of the Earth": six self-contained episodes, all ending with Earth's being destroyed in a different way. While writing the first episode, Adams realized that he needed someone on the planet who was an alien to provide some context, and that this alien needed a reason to be there. Adams finally settled on making the alien a roving researcher for a "wholly remarkable book" named The Hitchhiker's Guide to the Galaxy. As the first radio episode's writing progressed, the Guide became the centre of his story, and he decided to focus the series on it, with the destruction of Earth being the only hold-over.
Adams claimed that the title came from a 1971 incident while he was hitchhiking around Europe as a young man with a copy of the Hitch-hiker's Guide to Europe book, and while lying drunk in a field near Innsbruck with a copy of the book and looking up at the stars, thought it would be a good idea for someone to write a hitchhiker's guide to the galaxy as well. However, he later claimed that he had told this story so many times that he had forgotten the incident itself, and only remembered himself telling the story. His friends are quoted as saying that Adams mentioned the idea of "hitch-hiking around the galaxy" to them while on holiday in Greece in 1973.
Adams's fictional Guide is an electronic guidebook to the Milky Way galaxy, originally published by Megadodo Publications, one of the great publishing houses of Ursa Minor Beta. The narrative of the various versions of the story are frequently punctuated with excerpts from the Guide. The voice of the Guide (Peter Jones in the first two radio series and TV versions, later William Franklyn in the third, fourth and fifth radio series, and Stephen Fry in the movie version), also provides general narration.