Twelve years before the start of the series, the Nine-Tailed Demon Fox attacked Konohagakure destroying much of the village and taking many lives. The leader of the village, the Fourth Hokage sacrificed his life to seal the Nine-Tails into a newborn, Naruto Uzumaki. Orphaned by the attack, Naruto was shunned by the villagers, who out of fear and anger, viewed him as the Nine-Tails itself. Though the Third Hokage outlawed speaking about anything related to the Nine-Tails, the children — taking their cues from their parents — inherited the same animosity towards Naruto. In his thirst to be acknowledged, Naruto vowed he would one day become the greatest Hokage the village had ever seen.

Source: http://naruto.wikia.com/wiki/Plot_of_Nar...