I think it's a disease. I've been reading fanfictions for years, ever since Richard Dean Anderson quit Stargate SG-1, but I recently started writing fanfics. Scratch that, I've been writing them mentally almost as long as I've been reading them, but I'd never actually documented my fanfics until last month, when LB & I started writing Chuck drabbles. 35 drabbles between the both of us later, & I think you can officially say I'm hooked.
A quick tutorial for those of you who are fanfictions virgins, fanfics are basically fan stories regarding their favourite TV shows, books, movies, etc. With TV shows, for example, they can be rewrites of certain episodes or completely original stories, or even outrageously different from the TV show in that the characters are in high school or in space or in the Victorian era. Characters who are meant to be together (Chuck & Sarah, Booth & Bones, Annie & Auggie, Sam & Jack, & the list goes on & on) have a tendency to realize they're in love much faster in fanfictions than in the actual TV shows. Of course, fanfics also tend to include some beyond disturbing pairings (Wincest & Fred/George come to mind), which I'd rather not get into.
So, are you intrigued yet? Then I think it's time to introduce some basic fanfic teminology, so that you might avoid the mental scarring of accidentally stumbling upon a Dumbledore/Hermione romance (I still have nightmares). Definitions are courtesy of http://expressions.populli.net/dictionary.html
*AU/Canon= AU stands for Alternate Universe, where an author will choose to stray from the canon, or everything, person, event, statement, that happens in the show, movie, or book, and create events which are on their own timeline. Usually this is when an author will deny a character's death or act like an episode never happened or say "what if" the episode had happened differently, or they will act like the show stopped a certain place and keep writing as if there are no new episodes after that. Fan fictions that take place after the end of a show are not alternate universe, however, because there is no canon for them to contradict.
*Beta= An editor of fanfiction. Aka, a fanfiction writer's best friend.
*Crossover= A fan fiction which incorporates characters, events, places, ideas, etc from another fandom.
*Lemon/Smut= Any fan fiction containing graphic sexual situations that are described. If you're going to read it, be careful, because every pairing imaginable is usually represented.
*Mary Sue/Marty Sam= Any original character which is too perfect, too extreme, or otherwise badly done. Nobody likes a MS.
*OOC= Out of character. When a canon character acts in such a way as to be totally contrary to what they would in the series.
A quick disclaimer, not all fanfiction is good. In fact, a lot of it kinda sucks. But if you're addicted to a certain TV show/book/movie etc., & you like to read/write, then http://www.fanfiction.net/ is the place for you. Also, consider checking out http://www.fictionpress.com/, fanfiction.net's sister site for original independent stories.
Well, in the words of the adorable Porky Pig, that's all folks.