A fictional universe is a made up world that is used as the setting for one or (more commonly) many works of fiction. It is often used in books but can be used in any form used to tell a story, for example role-playing games, television or movies. It can be said that every work of fiction makes a world of its own. A fictional universe is used when things in a story become a part either of other stories, or of games or other things.
Fictional universes are most often used in science fiction and fantasy stories but they can be used in any type of fiction. A fictional universe usually has certain things in them that make them different from the real world. These things could affect anything from cities the author created to entire galaxies. In most fictional universes, the laws of physics are different to let things exist which commonly do not, for example, magic or space travel to other planets. Fictional universes may also take place in any time period during the past, present, or future.
However Fictional universes are inside our Universe as fiction exist in books, movies And books movies are inside the real universe...