The idea that God takes form to help humans understand an aspect of God, these manifestations are endless and represented by many different gods and goddesses
Appear on earth to restore Dharma and justice when there is too much evil in the world, the final avatar is believed to be Kalki who will destroy all evil
Rig Veda: 'Who really knows, who will here proclaim it, whence was it produced, whence this creation? The gods came afterwards, with the creation of this universe. You there knows whence it has arisen?'