Fan fiction is when fans of a book, movie, or any other kind of story pen their own versions using the characters or settings from stories they love. Here are some examples:

Alternate Universe (AU): This type of fan fiction can have the same characters and settings as the original work, but with a different ending. The different ending could be anything from a changed romantic pairing to a character’s death. However, the story could also take place in a different setting, a different time period and have a different plotline altogether, while staying true to the original characters.

Canon: Stays true to the plot of the original story. Instead of deviating, it expands upon an event or continues where the author left off.

Crossover: Characters and settings from one medium cross over and interact with characters and settings from a second one. For example, Lord of the Rings characters meet Harry Potter at Hogwarts.

Romantic or sexual pairings: Most fan fiction falls under this category. These pairings can be heterosexual or homosexual (known as slash fic) and may stay true to the plot.

Drabble: Very short fan fiction — usually exactly 100 words.

Ficlet: Longer than a drabble, but still noticeably short.

One-shot: Story with only one chapter. The author has no intention of continuing the story after the chapter is finished.

— compiled by Lewis Smith
— sources: fanfiction.net, harrypotterfanfiction.com, lotrfanfiction.com, livejournal.com