The Hitchhiker's Guide to the Galaxy, often abbreviated "HHGTTG", was written by Douglas Adams for BBC Radio 4.  

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 in 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.