Here Be Dragons
The Warp is a parallel dimension to that of real space. It is a realm of chaos energy that psykics are able to draw upon to fuel their powers. It is also called the Immaterium, the Sea of Souls, and the Chaos Realm. It is from the Warp that the denizens of chaos draw their strength and where their gods reside.
Often the Warp is described as a realm of chaotic energy that flows in currents which facilitate a warp ship’s progress. Storms and warp creatures are not unknown to exist in the Warp and time works differently in the chaotic dimension than it does in real space.
No trip through the Warp is ever truly safe, though there are routes that have been established as ‘safe’ for thousands of years.