Airbending, the manipulation of air, is based on Ba Gua Zhang, a defensive and evasive style revolving around circular movements and open-palm strikes. The multiple rotations of Ba Gua forms provide power to the strikes. Ba Gua Zhang means "The Art of Change," because the practitioners are always in motion and can switch direction seemingly at random. Ba Gua Zhang was chosen as the basis for Airbending because of its unpredictable nature.
Waterbending is based on Tai Chi. It is a defensive style that uses hardly any of the practitioner's energy. Instead, techniques in Tai Chi involve redirecting the opponent's energy. A common exercise in Tai Chi involves two practitioners pushing back and forth against one another's hands to get a feel for energy flow. Waterbending training has a similar exercise frequently practiced by the show's characters Aang and Katara: they stand opposite one another and send a tendril of water in a circle between them. The character Iroh incorporates Waterbending teachings when training Zuko, his nephew and pupil, to redirect lightning, although the two of them are Firebenders.
Earthbending is based on Hung Gar, a harder style than either Ba Gua or Tai Chi. Practitioners directly counters an opponent's attack with a hard defense and counterattack. Hung Gar is modeled after the movements of the Tiger and the Crane, using powerful hand and foot techniques from solidly rooted stances. In Earthbending, this solid rooting gives the practitioner more physical contact and spiritual connection with the earth in order to manipulate the earth element. Toph Bei Fong, Aang's Earthbending teacher, uses Southern Praying Mantis. This style focuses on light, precise footwork.
Firebending is the most energetic bending style, both in the show and in the fiery martial arts style that it's based on. Northern Shaolin employs leaping flamboyant kicks and powerful hand strikes that involve twisting the entire body and bringing the limbs to full extension. Many Northern Chinese styles heavily emphasize footwork because the mountainous terrain in China develops naturally strong legs. Although the movements may seem excessive, they rely on momentum to flow into the next technique in a form, putting the practitioner in position to attack or defend by using built-up energy. Another aspect of both Firebending and Northern Shaolin is emphasis on breath control. Internal energy, which powers body movement in the real-world martial art and Firebending in the show, comes from the breath, which in turn is identified with fire in Chinese and other Eastern systems.