Avatars are material appearances of deities on earth, and varying lists of avatars of Vishnu (who appear in Hindu mythology to destroy evil and it sources) appear in Hindu scriptures.
An avatar (Sanskrit: , IAST: avatara; Sanskrit pronunciation: [tar), a concept in Hinduism that means "descent", is the material appearance or incarnation of a deity on earth. Varying lists of avatars of Vishnu appear in Hindu scriptures, including the ten Dashavatara of the Garuda Purana and the twenty-two avatars in the Bhagavata Purana, though the latter adds that the incarnations of Vishnu are innumerable. The Vishnu avatars appear in Hindu mythology whenever the cosmos is in crisis, typically because the evil has grown stronger and has thrown the cosmos out of its balance. The avatar then appears in a material form, to destroy evil and its sources, and restore the cosmic balance between the ever-present forces of good and evil. 
