The planes sit in a layer cake structure, with small holes that connect each layer to its adjacent planes, called Gates. The planes are arranged as follows:

Celestia - The High Plane. Its inhabitants evolved through Light Ether to a sort of enlightened state of body, with silver hair and translucent skin. They keep to themselves and pay little mind to the workings of the other planes. After the War of the Open Planes, the Royal Celestian Courts decided to lock the plane to further separate themselves from the chaos.

Grindium - Highest of the Middle Planes. Due to the development of animal species rapidly overtaking the human populous, when the ethereal evolution took place, the now magickal creatures dominated the plane and the humans died out. 

Doegg - Middle of the Middle Planes. The symbiotic bond between humans and animals in this plane caused their ethereal evolution to bond them even further, creating human-animal hybrid races, commonly known as demihumans. The plane's population then divided by clan and set up regional boundaries, with clans warring over their region's control.

Arktivus - Lowest of the Middle Planes. Arktivus evolved in a wonderful balance between human and animal, eliminating any sort of imbalanced shift in their numbers. The development of magick was fueled by survival,a nd then by war, but it never stopped. 

Erosia - Innocence.

Beldam - The Nether Plane. Beneath the others, the lowest plane evolved through Dark Ether and it twisted their humans, animals, and plants into creatures of primal, bloodthirsty impulses.

Each plane has its own unique aura hue, and those that are born there also exhibit that aura.

Celestia - Silvery blue

Grindium - Purple

Doegg - Green 

Arktivus - Bright blue

Erosia - Dull white

Beldan - Dark red

Ages ago, the first magi researched the gates and found that by using the two aural hues in conjunction with rune magick, the gate could be locked or unlocked. This required a lengthy, complicated ritual, but the details were lost in time, along with the exact designs for the gate keys. This was when the Innocence Initiative was put into motion, and Erosia was double-locked. That meant that all of the gates to Erosia, from Beldan and Arktivus both, were sealed. They keys were destroyed, along with any information that could reproduce them. Because each key is unique, and the runes that locked the gate must be the runes that unlock it, there is literally no way to reopen Erosia to the planar passage.

In addition to an aural hue, each plane, save for Erosia, has an innately occuring ether.

Celestia - Light Ether

Grindium - Natural Ether

Doegg - Natural Ether

Arktivus - Natural Ether

Erosia - No Ether

Beldan - Dark Ether

Arktivus, Doegg, and Grindium all have innate Natural Ether, meaning that dark and light ether are not present there. In the event that dark or light ether be modulated in a plane of Natural Ether, it must be contained within a crystal or similar matrix, else the particles revert back to their innate resonance. The three natural ether planes are often referred to as The Middle Planes.