The void is an insubstantial realm in the world of Kill Six Billion Demons. The Wheel comprises the physical reality of the omniverse, with the void being the surrounding lack of existence, upon which the reality of the Wheel casts impressions. The Void is home to Angels and Demons, who are the only Inheritors capable of remaining there indefinitely.
During their reign, deities would often ride the void as a means of rapid transport throughout Throne, though some beings chose to live within the void, such as the Master of aesthetic.
Later, during the forging of the Wheel, the void would be populated by two races: The Angels, who were banished there by the demiurges before being returned; and devils, whose hot black flame was hurled there by the gods, before being masked and defined by Man.
The Void is a realm of nothingness, within which exists the multiverse that is the setting of KillSixBillionDemons. The Multiverse can be described by analogy as a burning wheel, and the 'stuff' of the void is in fact only the smoke and ash cast off by it; the shadow of reality impressing upon it. Due to this, like Throne, the void is littered with ancient corpses, either buried in the ground or floating about. The land is white and desolate and ill defined. The Road of Kings was built within the Void, as physical space as it exists within the Wheel has little meaning there.
The Void is home to the orders of Angels and Demons, who are able to persist there in fully realized bodies due to their strong flames of White and Black that make up their souls. Humans and other Perceiver races, having only a weak black flame, cannot maintain a body in the void, so far from the power of the Wheels flame. Instead, Percievers exist within the void as black shades; only partially corporeal and somewhat transparent. Remaining within the void for extended periods can cause shades to dissipate and fade away, making it impossible to live in the Void indefinitely.