Fan fiction (alternately referre to as fanfiction, fanfic, FF or fic) is a broadly defined term for fiction about characters or settings written by admirers of the original work, rather than by the original creators. The term usually applies to works that are not commissioned and unauthorized by the owner/creators and publishers of the original and usually (but not always) works which are not professionally published. Fan fiction is defined outside of original fiction, which exists within its own discrete, professionally published universe, and therefore outside of canon works within that universe. Most fan fiction writers assume that their readers have knowledge of the canon universe (created by a professional writer) in which their works are based.