The Hitchhiker's Guide to the Galaxy is the first of six books in the Hitchhiker's Guide to the Galaxy comedy science fiction "hexalogy" by Douglas Adams. The novel is an adaptation of the first four parts of Adams's radio series of the same name. The novel was first published in London on 12 October 1979. It sold 250,000 copies in the first three months. The namesake of the novel is The Hitchhiker's Guide to the Galaxy, a fictional guide book for hitchhikers (inspired by the Hitch-hiker's Guide to Europe) written in the form of an encyclopaedia. --- Also contained in: - The Hitch Hiker's Guide to the Galaxy: A Trilogy in Four Parts - The More than Complete Hitchhiker's Guide - Ultimate Hitchhiker's Guide to the Galaxy