Ethereal Plane

The "normal" world can be thought of as two layers that are connected: the standard plane (better known as the natural or physical world), and the ethereal plane; an invisible and unimposing layer that "binds" the natural world together.

The ethereal plane consists mostly (or entirely) of mana, a material that can be used to affect the standard plane. The manipulation of mana is the fundamental mechanic that allows magic to function.