A Reality is a seperate and completely different version of the world, of which there may be an infinite number. The strongest and most stable is called reality prime.So far, thirteen major branches off prime have been discovered. Realities are created and destroyed by enormous fluctuations in Chi' Karda. Examples:
Fourth- Much more advanced Technologically advanced than the other realities thanks to the remarkable visions and work of Hans Schtiggenschlubberheimer.
Fifth- Quirks in evolution led to a very tall human race.
Eighth- The world is covered in water due to much higher temperatures that were caused by star fusion triggered by an alien race.
Eleventh- Quirks in Evolution and diet led to a very short and robust human race.
Thirteenth- High levels of Chi'Karda led to a magic using human race, and is probably the source of all magic related stories.