An incarnation is a manifestation of God on earth. Lord Krishna in the Gita states: “whenever righteousness declines and unrighteousness prevails, I manifest myself. For the protection of the righteous and the destruction of the wicked, and for the establishment of religion, I come into being from age to age”. Thus God took human form again and again to destroy evil. This doctrine reached its fullest development during the Puranic period (A. D. 300-1200).
The avataras or incarnations reconciled the unity of the divine with the multiplicity of local divinities, thus absorbing tribal, racial and community gods. Of the many avataras, those of Vishnu are the most popular, the best known of them being Rama and Krishna. The avataras of the epics are intermediaries between man and the divine. God manifests himself in forms that can be appreciated by even the most unsophisticated.
Avataras are countless, for besides the popularly known figures any saint or spiritual teacher can be said to be an avatara to some degree, being at least in part if not fully an embodiment of the divine.