Wheel Cosmology

Wheel cosmology is the most common model used to explain the structure of the planes of existence. At it's centre is The Material Plane, with the echoes known as the Feywild and the Shadowfell. Surrounding them are the Elemental Plains and the elemental chaos. All these together make up the Inner Planes.
Connecting the Inner and Outer planes is The Astral Sea, which envelopes all. The outer planes, both the positive (good) and negative (evil), are also known as divine realms as they are the homes of various members of the Creed of the 21, as well as The Abyss and The 9 Hells. It is possible more planes exist, even other material planes, though no more are known.

_{Note: this picture is from the book and the names/locations of outer planes is inaccurate. I will make a world-accurate version soon}