The story is a world that has four civilisations, namely Spare Air (Water Tribe), Royal Land (Earth Kingdom), Air Nomads (Air Nomads), and the Nation of Fire (Fire Nation). In every nation there are people who are called Bender (bending, or in this case the controllers) that have the ability to control the natural elements according to their nations.
Control the natural elements of this art is a fusion style of martial arts and magic of natural elements. In every generation, there is someone capable of controlling all four elements, is being called as the Avatar, the spirit of the planet incarnate in human form. When the Avatar dies, he will be reborn in a nation that always turn alternately in accordance with the cycle of Avatars (Avatar Cycle), which along with the seasons: winter for water, spring for earth, summer for fire, and autumn for air.