In the context of a fictional universe, the canon comprises those novels, stories, films, etc., that are considered to be genuine or officially sanctioned, and those events, characters, settings, etc., that are considered to have existence within the fictional universe. This is the illusion of true fiction. The word "canon" originally meant the books which the Catholic Church officially chose to be included in the Bible - by extension, it means the authoritative "holy writ" of a fictional universe.