In the Cosmic Wheel model of cosmology, the Material Realm was the plane where all aspects of the fundamental cosmos converged. Also known as the Prime Material, or as "Ostmyr" to Commoners, the plane was composed of many opposing characteristics. Fundamental aspects of the Elemental Realms, Positive Border, Negative Border, Vivid Realms, and Umbral Realms bled into the Material, causing an ever-changing and beautiful environment where stability, disorder, good, and evil were all manifest. These conditions were particularly viable to create manifold forms of life, allowing all manner of creatures to thrive in the planes.
Being the only plane that intersected the Ethereal Border and the Astral Border, the Prime Material plane occupied an important position as a planar crossroads. As a result, all other planes could be defined in relation to the Prime.