Fanfic or fan fiction is nonprofessional fiction written by the enthusiasts of a TV series, movie, book, or comic book, which takes place in that universe.
It is not to be confused with faan fiction (the definition of "fan fiction" in Fancyclopedia 1 and Fancyclopedia 2). The extra a, as in faan, was added to distinguish that from this sort of fiction as well as from nonprofessional sf printed in sf fanzines — usually put out by relative neofen — which has generally been looked upon with disfavor because, with rare exceptions, if the piece were any good it would be published professionally.
Then too, people who write sf for fanzines generally learn little besides how to write bad sf for fanzines. The vast majority of active fans who’ve "gone pro" have been those who contributed relatively little fiction and a lot of essays and articles to fanzines . Roger Zelazny was a major exception to this rule, having contributed (as a teenager) a truly terrible sf story to Thurban I, one of the worst crudzines of all time, and then going on to a brilliant pro career writing science fiction some time later.
Contributors: Dr. Gafia