Cosmology is the study of the universe. The universe is divided into several planes of existence, within which exist worlds and other celestial bodies. The point at the end of time in all planes of existence is known as the Void.
Because of the universe's planar structure, it has sometimes been described as a multiverse. However, the various planes of existence within the periphery are properly considered to only constitute a single universe. Other parallel universes do exist, such as the split timeline created by the Time Heist.