Erudite itself was created when the thoughts and dreams of the gods became physical form. Essentially, Erudite's precursor, the United Plane, was created by being willed into existence by Ouroboros. As such, because of the intangible nature of the universe, magic and the supernatural are able to exist.
Realms are parallel worlds that occupy the same space of existence as others. In the time of the United Plane, all realms once existed in one world, but since the Shattering, these realms have since separated themselves, starting off as free-floating memories until they were given physical form through the work of an Aard'Vorn or some other method.
While it is possible to travel between realms, it is unknown how many there are. It is believed that because these realms were created based on thoughts that they are not entirely limited by physical laws. Some hypothesize the existence of realms that are too bizarre or incomprehensible for normal beings to actually exist in.
Everything within the spherical border of Creation's End is considered part of Erudite. While the majority of Erudite consists of numerous realms, the universe gets strange if one travels far enough although the distance is considered impossible to travel within 1000 lifetimes. Magical theorists believe that at the very edge of Erudite, the ether disappears and gives way to chaotic, nonsensical, impassable land formations where the laws of physics fail to follow a consistent pattern, and the rules of magic differ drastically. Hidden among the chaos are other fantastic realms collectively known as the "nexus between worlds". These realms have origins totally unrelated to Ouroboros although for a long time, there was no known way to enter them until some failed experiments with summoning spells determined that one can be accidentally sent outside of Erudite and into these realms, but to never return.
Despite the chaotic landscape, it is believed that the land forms eventually run out of ways to arrange themselves and begin duplicating. While having yet to find mainstream appeal to the magical community, it is said that should one go far enough, one would find numerous copies of Erudite with minute differences from one another.