Topic summary
Prime Material Plane
Extracted from the Wikipedia article Plane (Dungeons & Dragons).
Material Planes
The Material Planes are worlds that balance between the philosophical forces of the Outer Planes and the physical forces of the Inner Planes—these are the standard worlds of fantasy RPG campaigns. The Prime Material Plane is where the more 'normal' worlds exist, many of which resemble Earth. The 2nd edition Dungeon Master's Guide states there are several Prime Material Planes, but several other 2nd edition products say there is only one Prime Material Plane rather than several.