Fade

The Fade, known by some Dalish and humans as the Beyond, is a metaphysical realm that is tied to Thedas.
Mages tap into the Fade when they cast spells and are able to remain fully conscious while traveling there.

Chantry teachings

According to the Chantry, the Fade is a realm of primeval matter from which the Maker formed the physical world and all living beings. It is sometimes compared to a well of souls. It was the first realm created by the Maker, populated with spirits, the first of the Maker's "children". Growing unsatisfied with them she created Thedas and populated it with new, mortal creatures. Many spirits grew jealous of these new children. Mortals now refer to these spirits as demons, craving and emulating the basest desires and sins of mortals.
The Chant of Light states that a city lost in the Fade was once the seat of the Maker. This glorious paradise was referred to as the Golden City. Supposedly, vile Tevinter magistrates attempted to physically enter this city and blackened it with their prideful ambition.
When the Chant of Light spreads to all four corners of the world, the Maker will forgive mankind and return, restoring the Golden City.

Elvish teachings

The Dalish refer to the Fade as the Beyond and believe that it is a holy place that was once the home of the gods. They also tell that the gods now lie imprisoned in the Eternal City at the heart of the Fade while the Dread Wolf roams, gleefully feasting on the souls of the dead.

Landscape and Denizens

"There is no geography in the Fade. Place and time are far less important than concepts and symbols."

Few know anything about the Fade, other than its existence and relation to the Maker. Most see it as a place where souls go after passing from their mortal lives.
Many mages from the Circle of Magi have been there, as in order to become a full mage one must enter the Fade and slay a demon. This ritual is known as the Harrowing.
Intellectuals who have read reports from this ritual would know that the Fade is a twisted, frightening world of dark rock and raw emotion. It is always night there, and gravity affects nothing equally. An island with a black city can always be seen up above the horizon, no matter where in the Fade you are. Even the most powerful demons seem to keep their distance from this place.
The Fade may appear as something else entirely when shaped by dreams. Much of the Fade is split up into regions belonging to the spirits or demons that live there, and they change the landscape of the Fade to emulate that which they see in the minds of mortal dreamers. They copy locations, objects, people and concepts of the real world, often in a cruel or confusing way. These copies are nowhere near consistent, and fluctuate according to the movement of the dreamers.

Type

Dimensional plane