Manual of the Planes

The Manual of the Planes is a manual for the Dungeons and Dragons role-playing game. This text addresses the planar cosmology of the game universe, including its various planes such as "Baator", the "Abyss", "The Happy Hunting Grounds", "The Concordant Opposition" and the "Prime Material Plane." It is a considerable expansion to the manual Deities & Demigods, which also had a section devoted to the subject.
See more at Wikipedia.org...