hindus believe that vishnu has many important avatars. the vamana avatar was the fifth avatar. in this avatar, vishnu was in the form of a human.vamana avatar is basically in the form of a bramhin(a caste in hinduism which is responsible for ancient spiritual, cultural, educational activitiesand the highest in the varnas) was taken for a demon king 'bali'. lord vishnu in this avatar asked bali to offer him 'three feet land' as a form of offering a king offered to a brahmin as a goodwill during ancient times in hindu culture. the story goes when king bali captured the adobe of hindu demigods and caused them a fierce battle. 'aditi' - the mother figure of demigods in hinduism prayed to lord vishnu and pleased by her prayers, lord vishnu appeared and assured her a boon. in a thought of revenge , she wished that may bali loose his whole wealth and power."