Fan fiction or fanfiction (also fanfic, fan fic, or fic) is a fictional work of writing about characters or a setting from another work of fiction. Usually it is created by fans who wish to see their own version of a story that was created by the original author. This can be a new storyline, new characters, alternative endings, beginnings, etc.
Usually the plot of fan fiction centers around an event or relationship that the fan would like to occur, but know it likely will not. Sometimes fan fictions contain people from the same fictional universe who the fan would like to be together, and sometimes they could be from a completely different universe. Basically, anything that the fan would want to happen, is fair game in fan fiction.
Fan fiction can either be in the canonical fictional universe of its subject (referred to as ‘canon’) or exist outside of it. Most fan fiction is read by other fans of the subject; therefore, the author can assume they don’t have to explain things already known within this universe.
For example, fans of Harry Potter are known to make fan fiction featuring the characters of Draco Malfoy and Harry Potter. These are two characters who are both canon to be heterosexual, but fans often pair them together in fan fiction. It is the classic hate-to-love you trope that is popular within literature.
Fan fiction is usually not commissioned for by the original author, and not usually published professionally. However, in recent years fan fiction has become a huge part of popular culture. Works of fan fiction have been altered and have become their own works of literature. An example of this is with the Fifty Shades of Grey series, which has gone on to become a successful movie franchise. The original title of the work was Master of the Universe and contained Bella Swan and Edward Cullen as the main characters.
Fan fiction is very popular in current popular culture. In the young adult novel, Fangirl by Rainbow Rowell, the main character Cath Avery writes a well-known fan fiction about a fictional novel similar to Harry Potter. Rainbow Rowell went on to write her own version of the fictional fan fiction her character wrote, and published it under the title Carry On.
Fan fiction is a way for fans of something to be creative and make their own version of the story they love so much.