The Marvel Universe (MU) is a comic book fictional universe created by Marvel Comics. The MU is where most of the main stories published by Marvel Comics takes place. The MU is actually just one of an infinite number of different universes. Each one can be called a Marvel universe, but the term is commonly used for just one. This one is also called Earth-616 when looking at all the universes as a group. The other universes vary from very similar to the Earth-616 universe to completely different. This lets the writers create stories which have a large effect to the universe they take place in without affected the main universe used by all of the writers as a group.