Aether, also known as Mana and Spiritual Power, is a metaphysical ubiquitous energy force that is the basis of all life and matter. Aether is a chaotic and everchanging force that can shapeshift itself into many forms, from solid objects to liquid or gaseous materials. When large forms of aether are shaped into order by themselves or by the work of someone, they become Planes. Aether is constantly being generated at the center of Genkrad, known as the Planestorm, it is only there that it exists in it's pure, original, chaotic state.
Forms with strong aether develop what's called Spirit, which what makes a inanimate being move and gain life. Beings with spirit are known as Mono, and their reason of existance is unknown, but they have existed since the beginning.
Forms with even stronger aether develop what's called the Mind or Soul. These beings, known as Stereo, can reason, communicate, think rationally and have a conscience. Some can even control and manipulate a small, but relative amount of aether.