The Planes

The First “Dimension”: The Material Plane The Feywild The Shadowfell The Ethereal Plane
The Second “Dimension”: The Plane of Fire The Plane of Water The Plane of Air The Plane of Earth The Weave / The Pools
The Third “Dimension” The Astral Plane The Plane of Order and Chaos The Plane of Creation

There are several Plane like places mentioned in Campagin 3, The Plane of Dreams, The “Moon”, The Underdark, Hell, etc. Many of these are called Demi-Planes, these are Planes that exist in other planes as smaller individual realms that rely on the corresponding dimension to exist.
The First Dimension is the Reality Dimension, this makes the physical world and the complexities that interconnect all life. The Second Dimension is the Fabric that creates, it's what the first dimension is made of and more, the Primoridal raw planes The Third Dimension is the Far out, the distant, and the Philosophical. The home to the Theoretical. Dreams and Fears, Heaven and Hell, Notions of hope, Power, gods. Etc.

Type

Natural