Avatar: The Last Airbender takes place in a fantasy world, where human lives, many fantastic animals, and spirits. Human civilization is divided into four nations, Water Tribe, Earth Kingdom, Air Nomads, and the Fire Nation. In every nation there are people who are called Bender (literally means "bending", but in this case is considered "controller") that has the ability to control the natural elements according to their nation. The art of controlling this natural element is a fusion style of martial arts and magic of natural elements.
In every generation, there is someone who can control every element, is called 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 Avatar cycle, which along with the seasons: winter for water, spring for earth, summer for fire, and autumn for air. Legend has it that the Avatar must learn the art of controlling elements in accordance with the order, starting with the original elements of the Avatar, but sometimes it can dilewat order if circumstances force. Study the elements controlling the opposite of the one original element is extremely difficult because of different martial arts styles and doctrines.