The Backrooms/Dimension

The Backrooms is a major location of the series. It's a pocket dimension outside of the normal reality. The origins of its creation is currently redacted by M.E.G.'s Overseers. People can get there by no-clipping out of the normal reality.

Description
According to M.E.G.'s Overseer C, The Backrooms is a dimension that resides outside of normal reality known as "Primus Reality". The Backrooms are a series of 'Levels', with each one having varying levels of quantum stability, manifesting as large or small areas that mirror normal reality in some ways. Many have considered them 'liminal spaces', 'heterotopias', or 'déjà vu enducing nightmares'.

Most people who find themselves in the backrooms either join a colony, outpost, or major faction, or become nomadic travelers, called wanderers. Any being that would not exist in the real world under normal circumstances, and is believed to be created by, or only exist in the Backrooms, is referred to as an Entity.

Biology
While each individual Level of the Backrooms may or may not be finite, there is likely an infinite amount of Levels. Attempts to map out the physical placement of each Level outside of normal reality have been made, but this is considered a fruitless effort. Levels seem to lead into one another at complete random, leaving the order of them sometimes up in the air. The complete nature of reality is impossible to keep track of as it shifts randomly and doesn't follow the laws of physics unlike the normal reality. Daniel, who is apart of the research group of Base Alpha and somehow got into the Manila Room, says the chances of actually escaping out of The Backrooms is extremely difficult due to the Levels' growing difficulty in Entities with every entry.

Levels
M.E.G. categorized the first 1000 Levels as "Cluster I" as they began exploring the Levels of The Backrooms. Cluster II can only be unlocked to Wanderers only if they get past Level 999 which the final and most difficult Level of the entire Backrooms so far.

Theories/Speculations

 * The Backrooms can subject and expose Wanderers to traumatizing visuals using déjà vu that cause guilt to aforementioned Wanderers in some Levels, which could mean the reality itself is somewhat sentient to an extent.
 * It is speculated by Daniel that The Backrooms is actually just an alternate reality that shares a dimensional plane parallel with the normal reality.

Trivia

 * You can master no-clipping to travel between the two dimensions, doing it by will, only one to do this so far is Aiden.