The Void is part of the Dungeons & Dragons cosmology, and first appeared with the introduction of Planescape. It is a place, which exists between the planes, and touches everything. The Void, despite its name is neither empty, nor uninhabited but is composed, mostly, of nothingness. Certain individuals are able to utilize the Void for power (such as the Player Class: Void Disciple), but any direct interaction with it is touchy, at best, and only experienced mages or planar travelers should attempt at going there.