Technically refers to fan fiction, stories written by fans on existing works. However, in the impro community, the term has broadened in meaning to include stories that aren't based on particular works.
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
Short for "fan fiction," this is a fictional story written by a fan about a particular show. While many focus on relationships between characters, others focus on furthering certain plotlines of the show.
a creative work written for fans by fans
a story that somebody writes about charac- um, intrepid fellows such as yourself
a story written in the style or universe, or using the characters of another author who's work you like
A story written by fans that involves characters from an existing anime series. Usually written in installments and published on the internet, the content ranges from story continuations to improbable situations to erotica.
A work of fiction written by a fan and based on a popular anime or manga title.