What is a Demi-Realm?

A Demi-Realm is similar to a realm in many aspects however there are a few distinct differences.
 * A realm is infinitely expansively. A Demi-Realm is limited in size by the heavy magical power cost used to create it.
 * A realm cannot be destroyed by anything other than the First One, not even Sevarog in his prime could do it. A Demi-Realm can be destroyed with the equivalent amount of magical power used to create it.
 * A realm cannot be located within another realm, since realms are infinitely expansive it's impossible to travel between realms without a portal or through other magical means. Demi-Realms can be connected to other Demi-Realms. Azukar's Tent is the only known Demi-Realm that is capable of being inside realms