"A summary to explain the existence of different planes within existence at large, in very general terms."
EXISTENCE OF PLANES
Planes exist in all forms and manners, each exemplifying a particular aspect. Most every plane has creatures indigenous to it that embody that aspect of the plane they belong to. Though interconnected these realms appear to exist in unison with one another and portals or other magics are required to go from one to another. These planes are all separated by what is called The Veil, also referred to as The Curtain. Whichever plane a creature is indigenous to, referred to as anchored, is where they will return if killed while in another plane; however when killed on another plane a person's body and spirit will return to their anchored plane, not their items or other inanimate objects.
DOMAINS IN PLANES
Most planes fall under some sort of rulership. Many planes are the domain of a particular god, though other beings of power may have their own domains as well, often within or part of a greater plane, like nobles ruling in a kingdom. Some domains span across multiple planes. Notably there are two planes that appear to be unique in that their domains are not ruled over by a specific deity or entity: the Fae Plane and the Mortal Plane.
THE DIVINE DOMAINS
These planes are under the direct rulership of a god. Reflecting the personification each god embodies, divine domains greatly differ from one another in its inhabitants, appearance, and physical and magical continuity. More often than not celestials and infernals are found in these domains, but other creatures may be as well. This is entirely dependent on the god. It is here that the gods wield their greatest influence and power.
THE ELEMENTAL PLANES
The elemental planes are all linked to its appropriate, corresponding god. Summoning an elemental is theorized only to be possible by summoning them from each of these planes, the four primary being: earth, fire, air, and water.
THE FAE PLANE
Home to the Fae, this plane is said to have been first created by the gods, much like the Mortal Plane, while simultaneously claimed by the Fae it has always existed without the gods. The inhabitants of this plane are imbued with magics that work extremely differently than other beings and whose properties appear entirely foreign in concept. Immortal beings themselves, the Fae Realm appears to have some sort of connection to the Mortal Realm, but the exact manner of which is unknown.
THE MORTAL PLANE- ARIEL
No one god may lay sole claim for the creation of this plane, as it took the divine power of many to do so. The tale of the creation is recorded in the Book of Foundations, the collected works lost but pages are sometimes discovered as rare as they are. With the culmination of many gods being involved in its formation it thereby means no one god has it under their dominion. In this realm all manner of mortals are found, with each of their creations influenced, and involvement varied, by different gods in different manners. All beings indigenous to this plane are not innately immortal, though some of their life expectancies are elongated by their limited abilities to be resurrected after death. The Mortal Realm is named Ariel, but the origin of the name is unknown, the answer only to be found in lost texts.
THE VEIL / CURTAIN
The Veil is what lies between all planes in existence, surrounding them and connecting them. Not a plane in and of itself it does hold its own properties, and possibly creatures, serving as both barrier and gateway.