Outer Planes
The Outer Planes is a term from Dungeons & Dragons introduced in the Planescape setting. It is a way of collectively referring to the various alignment-based planes that are the backbone of the Planescape setting, as these planes exist "outside" of the Inner Planes and are subsequently seen as the most important parts of the multiverse, at least by the residents of Sigil. The Outer Planes can be divided by general alignment category into the Upper Planes (Good), Middle Planes (Neutral) and Lower Planes.