Fan fiction or fanfiction (also abbreviated to fan fic, fanfic or fic) is fiction about characters or settings from an original work of fiction, created by fans of that work rather than by its creator. It is a popular form of fan labor, particularly since the advent of the internet.
Fan fiction is rarely commissioned or authorized by the original work's creator or publisher, and is rarely professionally published. It may or may not infringe on the original author's copyright, depending on the jurisdiction and on such questions as whether or not it qualifies as "fair use" (see Legal issues with fan fiction). Attitudes of authors and copyright owners of original works to fan fiction have ranged from encouragement to rejection or legal action.
Fan fiction is defined by being both related to its subject's canonical fictional universe (often referred to as "canon") and simultaneously existing outside it
I still remember what my first one was. 
I haven't read any in a while though.