Avatar: The Last Airbender (Avatar: The Legend of Aang in some regions) is an American animated television series that aired for three seasons on Nickelodeon from 2005 to 2008. Avatar: The Last Airbender is set in an Asiatic-like world in which some people are able to manipulate the classical elements by use of psychokinetic variants of Chinese martial arts, known as "bending". The show combines the styles of anime and American cartoons, and relies on the imagery of various East Asian, Inuit, Southeast Asian, South Asian, and New World societies. Therefore, whether or not the series can be considered as an anime work is often discussed. Wikipedia
Katara: (opening narration) Water... Earth... Fire... Air. Long ago, the four nations lived together in harmony. Then everything changed when the Fire Nation attacked. Only the Avatar, master of all four elements, could stop them. But when the world needed him most, he vanished. A hundred years passed and my brother and I discovered the new Avatar, an airbender named Aang. And although his airbending skills are great, he still has a lot to learn before he's ready to save anyone. But I believe Aang can save the world.