What are Planes?
Planes refer to the different areas of existence across our worlds. There are two known planes, as well as a long stretch of grey area in-between the two known as the paracline. These planes may also be referred to more colliqually as the veil. The plane that humans live in is sometimes called The Above, and the plane belonging to nonanthropy is called The Below, hence phrases like "As Above, So Below" being commonly used to describe the relationship between the two. Of course, The Below is not literally below us, but it is often depicted that way for simplicities sake. The truth is, The Above and Below can be in any direction up, down, left, or right.
The Below is unique in that much of it is nothing more than The Void; an empty black space where it is thought that very few entities dwell- though the area is know unknown, it's hard to truly say for sure. Some rumor that it is where the dead and lost reside. Small pockets within create different general living areas with higher populations, but they are usually quite small, often built as homes for entities and potential living-mates.
What Does The Below Look Like?
The Below has many different areas, some highly populated, some with very few inhabitants. Most of these areas are broken up by long stretches of Void. The experience is often extremely disorienting, distressing, and hard to acclimate to for humans, hence why there are very few examples of what seeing it is truly like. However, some accounts have said that the Below is usually very dark, as there is no natural Sun. It is often composed of barren or forested lands, with most light coming artificially, if there is any at all. It is said to be very difficult to see, and that the sounds are grating and foreign to the ears. There are occasional makeshift towns within the Below, but most entities seem to prefer living in their own wilderness. Some areas of the Below are said to lack color, or are colored in a strange light. Despite all these accounts, it is hard to say what is true and what is only said because the human experience within the Below is not a pleasant one. One account of a now deceased planesdiver describes their time there as having "lakes of black liquid, snowing ash, and dim, lantern-lit ambience, steeped in red light."
Can You Travel To The Below?
Yes, though with extreme caveats. Most humans do not know how to travel to the Below, and this is for good reason. It is a sparse, often disorienting environment, with very few humans living to tell the tale, and few entities willing to share details on their own home across the veil. If you are a human, it is not recommended to travel there.
Most entities, Interlopers included, are fully capable of travelling across the veil, and the more it is done, the easier it becomes to achieve.
Do Entities Live In The Below?
Yes, they do. However, most entities prefer to keep to themselves when inside of it. Many entities also prefer to live in the Above for a variety of reasons, such as predation. A large number of entities use the Above as hunting grounds, and the Below for resting or hiding. Most entities do not live in the paracline, but there are exceptions in some cases.