Premise: Avatar : The Last Airbender ( Avatar : The Legend of Aang in some regions ) is an American animated television series that aired for three seasons ( referred to as `` books '' in each episode 's title card ) on Nickelodeon from 2005 to 2008 . The first season 's success prompted Nickelodeon to order second and third seasons .
Hypothesis: Avatar: The Last Airbender aired for three series.
Label: ENTAILMENT