Alternate Universe This refers to fanfiction that takes a character or characters out of their original venue and places them in another universe or in another time period. For example, changing the nature of the character (a character turns out to be an elf, sprite or other fey creature) or placing the characters in the wild west or on a space station, if that's not the characters' original environs. Also denoted as A/U.
Canon Facts taken from the episodes of the show, the books or the film on which the fandom is based. This is what defines the universe. It provides the context for the characters.
Crossover A story or novel that combines two or more fandoms by taking a character or characters from one show, film or book and placing them into another show, film or book. For example, a character from one show dies and he turns out to be an Immortal from the Highlander universe. Or a story that combines two separate shows and sets of characters, such as a Sentinel/Highlander crossover.
Fan Fiction Amateur fiction set in universes and using the characters created by other people in television shows, movies and books.
Fanon Popularly accepted information or characterization that comes from the imagination of the fans rather than from canon. Fanon usually originates in fan fiction.
First Time Fan fiction in which a couple has sex for the first time.
Gen Stories that are non-homosexual in nature. A general story in which romance or erotica plays no significant part.
H/C This refers to hurt/comfort, the practice of making a character suffer physically or mentally in order to elicit comfort from the character's partner/lover/friend.
Het Romantic and/or sexual relationships between characters of opposite sexes; heterosexual. Also known as Adult.
LoC Letter of Comment. A letter or e-mail sent to an author, commenting on the author's work.
Mpreg Denoting male pregnancy, mainly used in fan fiction where a male character is somehow, cleverly, made to endure the traditionally female condition of physically carrying a child and giving birth.
Multimedia Whether this is used in terms of a zine, song vid, etc., this means that it involves more than one fandom.
Slash Stories that depict a romantic and/or sexual relationship between characters of the same gender. This usually refers to male/male pairings, as that is the dominant type of story, but it also refers to female/female pairings. The term originated in Star Trek fandom as Kirk/Spock (or K/S) stories. Slash refers to the "/" between the names.
Song Vid A fan-made music video in which music and carefully chosen video clips from favorite tv shows or movies are combined.
Zine Originally "fan magazine," which became "fanzine," and is now "zine" (pronounced zeen). A novel or collection of stories written by fans, bound into a book.