Waterbending, one of the four elemental bending arts, is the hydrokinetic ability to control water, as well as its many forms. This type of bending is utilized by the people of the Water Tribes, who are divided into the Southern, the Northern, and the lesser known Foggy Swamp, each with their own unique bending style. Water is the element of change. The moon is the source of power in waterbending, and the original waterbenders learned by observing how the moon pushed and pulled the tides. The Water Tribes are the only people who did not learn bending from an animal, though the Moon and Ocean Spirits took the form of koi fish near the beginning of the avatar world. The fighting style of waterbending is mostly fluid and graceful, acting in concert with the environment. Foggy Swamp style waterbending, however, is more rigid and straight. Waterbenders deal with the flow of energy; they let their defense become their offense, turning their opponents' own forces against them.