From Fan History Wiki
Fan·fic n. Informal: Fiction written by fans as an extension of an admired work or series of works, especially a television show, often posted on the Internet or published in fanzines. 
Fan Fiction is, at its most basic, fiction written by fans. A more broad definition might include that in order to be classified as a "fan work," at least some elements must be of an identifiable "non-original" nature; i.e., the mere influence of the vast history of oral and written tradition including recognizable themes does not, in and of itself, define a work as fan fiction. The influence must be identifiable, and for some people, attributable. The doomed romance of Romeo and Juliet is not a unique theme, merely a unique execution of a popular theme. In order for a work to be considered "fan fiction" of Romeo and Juliet, utilizing the place or time or some of the characters or even lines from Shakespeare's work must be done in a substantiative way. Merely quoting him or having a character who quotes lines or make reference to the play, does not in and of itself make the work fan fiction. However, a story that somehow miraculously revives one or both the young lovers and follows them through the period after (or even before the setting of the play) could, arguably, be called fan fiction. Having Mercutio run off to a forest and meet Puck from A Midsummer's Night Dream might also be considered fan fiction.
That said, there is some debate both within fandom and in the broader academic, publishing, and production world, as to whether or not the definition of "fan fiction" must also include the word "amateur." Alternately, some argue that all derivative work is fan fiction in one way or another. There can be little doubt that popular works (and even less popular works) available to the public sphere have always had fans, just as they have always had critics. Fan fiction is merely a tangible response to such works.
Currently, fan fiction as portrayed in magazine, newspaper, and even Academic articles, is linked to mass media. The widespread availability of books, television programs, movies, and other media combined with the on-site of broader access to the World Wide Web as made the sharing and exchanging of fan created derivative works far easier and more common.
Star Trek is widely considered to be the critical point where fans shifted in large numbers from passive enjoyment of a media property into an active and even, yes, fanatical, demand for more product, regardless of whether it was produced by the original creator or even sanctioned by the controlling entities. Even before the advent of the Internet, fans began creating their own stories, their own analysis of the existing work, adding to it, changing it, creating entirely new areas in which the media entity known as Star Trek could be enjoyed outside of a weekly television broadcast.
When editors Sondra Marshak and Myrna Culbreath compiled the stories contained in the book, Star Trek: The New Voyages, in 1976 it was widely understood that the authors providing content were avid and active fans of the show.
There were no doubt other periods and properties where a media source provoked an impassioned response (The Baker Street Irregulars, for one -- consisting of fans of the Sherlock Holmes novels) but Star Trek appears to have provoked a far broader response that was possibly also opportunistically large enough to invoke interest not just in fans but in traditional news and media coverage. The fans were very vocal and public in their adoration.
Webster's Dictionary online attributes the first usage of the term fan fiction to 1944: Main Entry: fan fiction, n.:a fictional account written by a fan of a show, movie, book, or video game to explore themes and ideas that will not or cannot be explored via the originating medium; also written fan fiction, also called fanfic , however, no additional citation is offered in the short entry.Copyright as we understand that term today.
- fan fiction - Sometimes improperly used to mean fan science fiction, that is, ordinary fantasy published in a fan magazine. Properly, the term means fiction about fans, or something about pros, and occasionally bringing in some famous characters stf stories. 
- Fan fiction: (also 'fan fic' and 'fanfic') Stories written by fans using characters created by others in films, TV series, books, comics, and sometimes real-life. Fanfic used to be most commonly associated with science fiction, specifically Star Trek fandom. In the early days of science fiction fandom, fan fiction seems to have been simply original stories written by fans, not necessarily about someone else's creation and characters. Because of the growth of a sense of "If it's good enough to read, it's good enough to sell; if it hasn't been sold, why bother to read it?" snobbery among science fiction fandom, fanfic fell by the wayside until Star Trek made it's appearance. Fanfiction, anymore, is inherently unsellable work. Because the original copyrights to properties such as Star Trek, The X-Files, and other shows, books, movies and video games, are held by people other than the fanfic writers themselves, anyone attempting to sell their fanfics for profit run the risk of being slapped with an infringement lawsuit.
- The Internet has lead to another explosion of fanfic, since reproduction costs are almost nil and audiences can be easily found. Fan Fiction and fanfic are generic terms that cover several subgenres.
- A bias against fanfiction persists to this day. There are those who do not consider writing fanfiction to be the same as 'real' writing (i.e., writing original works, usually for publication). Fanfic is stereotyped as being poorly written, full of cliched plots and character interaction, and stuffed with self-insertion characters who are really the author badly disguised. Like any stereotype, there are grains of truth to the above. There are also fanfics that are sometimes better written than the original material they're taken from, sometimes because they can do things the movie/show/book/game/people couldn't do. This is especially the case for TV shows, where things can't always be shown because of network censors.
- By the same token, there are stories that are badly done and amateurishly written...but then again the same authors would most likely be creating badly done and amateurishly written stories if they were creating in their own universes. Why? Because, quite simply, they're amateurs! They haven't learned what it takes to tell a good story yet, so of course they're going to fumble along. Fanfiction can allow novice writers a chance to write stories with characters and settings they are comfortable with, while they work on creating their own voice and style. If they move on to creating their own original works, so much the better (at least in my opinion), but if not, so long as they're writing things they enjoy and their readers enjoy, then that's good too. (Rogow, 110-111)
- (abbreviated as fanfic / fic)
- fan + fiction: Story based on either characters or places, organisations, concepts in general of an official artwork, such as a videogame or a movie, written by a fan of it. The author uses these elements to create a story of his/her own conception. These stories are not official, they express the author's views on the elements s/he describes and inspirations derived from them. Some are exceptionally good too!
- (FYI: Movies of religious/historical content are fanfiction too in a sense. Only the heroes there are dead and cannot claim the copyrights...) 
- Fictional Stories created by fans based on characters from a movie, tv show, video game, or novel. 
- Fanfiction (Fanfic): Fiction written by fans of a particular fandom involving characters/places/scenarios from said fandom. Done mostly for fun and covered with disclaimers to prevent the copyright holders from suing them.
- Fanfiction - fiction based on something that already has a plot and characters (books, movies, shows). A fan fiction follows the major characters/plot of the story, only inverting a few details unless the story is an AU. A Fanfiction is simply a "what if" situation. 
- You hear the word fanfic in almost every anime-related site you go to. I'm sure most of you know what that is, but for those who don't, allow us to explain.
- Formally, it is called fanfiction, but it is often known as fanfic or fic. This refers to all stories written by fans of a certain TV program, movie, book or event. It's the own viewpoint of a fan, including the what ifs, and it comes in different forms. Thus, it doesn't necessarily follow the original plot. It may be of any length, and of any type. It depends on the author. Also, fanfics aren't written for money or the like, usually, fanfics are written plainly for entertainment purposes. See, fanfic = fun fic?
The following definition dates to October 2003 :
- Fanfiction: Occasionally culturally acceptable form of copyright theft. 
- This does not refer to all fiction written by f ans, because a lot of fans write original stuff. This means stories about charac ters in popular shows, books, plays, etc. A remake of Sweeney Todd using the ch arcacters from Cats, or a story where Captain Kirk fights Darth Vader would be f anfic. See slash. 
- Fan Fiction - fans writing or drawing media characters in ways the original author had not depicted them, giving characters new depth and detail, and occassionally taking them places viewers didn't want them to go. fanfic is created for the love of the genre, not for profit. 
- Fanfic - a story that is written by a fan and is based off of an established continuity, solely for the purpose of continuing the story or altering the storyline 
- fanfiction (fanfic, fan fic, fan fiction, fic) - Fiction written by fans about a TV show, game, book or movie. 
- fan fiction - This is a pretty obvious one, and you probably wouldn't be here if you didn't know what it was. Fan fiction is a form of fiction that incorporates aspects of another work (or collection of works) of fiction. It will oftentimes incorporate characters, plotlines, and other aspects of the world in which the original idea exists. In the case of Pokémon, fan fiction either incorporates characters from the Pokémon franchise in a more realistic situation, incorporates original characters into the Pokémon universe, or leaves the Pokémon characters in their world and instead develops additional, non-canon stories of the goings-on of that universe. Contrary to intuition, fan fiction does NOT have to be written by, a fan; it could, for example, be commissioned (although the legality of this is highly debatable) to be written by a non-fan yet still be considered fan fiction. 
- Fanfic: Stories written by fans of a show,manga, movie, book, etcetera. Non-profit work, and not intended to infringe on copyright. 
- What is Fan Fiction ?
- Fan Fiction is original writing set in a universe widely known from TV, movies or even other books. 
- 7. fan fiction. Most people outside of the fanfic community probably think (if they think about it at all) that fan fiction is the exclusive domain of SF and fantasy fans. While this was once true, it’s certainly not true any more, and both the name and some of the associated terminology of fan fiction originated in SF fandom. Some of these associated terms are slash (fiction that depicts a sexual relationship between two characters) and Mary Sue (a character that acts out a blatant wish-fulfillment of the author or a story featuring such a character), both of which originated in Star Trek fandom. Curiously, fan fiction was originally used to refer to amateur fiction written about fans themselves, rather than amateur fiction written using the characters or settings of an existing work. 
- Most fan fiction is brand fiction, but brand fiction itself encompasses a much broader universe. by Melissa Sepe on RazorFish on February 10, 2010
- Fan Fiction. A How To From Idea to Finished Product: Ideas by dawnofme on February 10, 2010
- Io9 posted this discussion of fanfiction writers turned pro today. I love io9, I read it pretty much daily, but I have to say that I inwardly cringe a little bit when they decide to dip their toes into fandom’s waters. by 13th-blackbird on February 10, 2010
- Brown, Scott. "Scott Brown on Sherlock Holmes, Obsessed Nerds, and Fan Fiction." Wired 20 Apr. 2009. 28 Apr. 2009 <http://www.wired.com/techbiz/people/magazine/17-05/pl_brown>.
- The Fan Fiction Phenomena - Young, Cathy, Reason Magazine, February, 2007 
- Rewriting the Rules of Fiction - Jurgensen, John, September 16, 2006 The Wall Street Journal Online 
- Fan Fiction as Critical Commentary - Jenkins, Henry, blog entry September 27, 2006 
- “Fanfic”: force of nature - Nielsen-Hayden, Teresa, Making Light blog entry April 22, 2006  
- For the love of... - Casimir, Jon, November 1, 2002, The Sydney Morning Herald 
- Destina's Fan Fiction FAQ - Destina 
- Wikipedia's entry on Fan fiction 
- Legal Fictions: Copyright, Fan Fiction, and a New Common Law - Tushnet, Rebecca, Loyola of Los Angeles Entertainment Law Journal, 1997 (17 Loy. L.A. Ent. L.J. 651)