In a lost age, the world is divided into four nations: Water Tribes, Earth Kingdom, Fire Nation, and Air Nomads. Within each nation, there is a remarkable order of men and women called the \"benders\" who can learn to harness their inborn talent and manipulate their native element. Bending is a powerful form combining martial art and elemental magic.
In each generation, only one bender is solely capable of controlling all four elements. That bender is the Avatar. The Avatar is the spirit of the world manifests in human form. When the Avatar dies, it reincarnates into the next nation in the cycle. Starting with the mastery of his or her native element, the Avatar learns to bend all four elements. Throughout the ages, the countless incarnations of the Avatar have served to keep the four nations in harmony.