By Stephen Knapp
An avatara is an incarnation of God. Whenever God descends to earth in any form then He is an avatara.
An avatara is a descension of one of the forms of the Lord. There are numerous forms of God who descend into the material manifestation from the spiritual worlds to help carry out particular pastimes or maintain the material creation, as well as attract the conditioned souls to return to the spiritual domain. The ten most important avataras of Vishnu include Matsya (fish), Kurma (tortoise), Varaha (boar), Narasimha (man-lion), Vamana (dwarf), Parasurama (the warrior with an axe), Rama (the perfect king), Krishna (God of love), Buddha, and Kalki (God on the white horse). The Kalki Avatar is yet to come. Hindus believe that the Kalki Avatar will come in the future at the end of this age of Kali-Yuga and bring back the refined age of Satya-Yuga, the Golden Age. [You can learn more about Lord Kalki from the article “Kalki: The Next Avatar of God” on my website.]
Each avatara has a definite purpose. Lord Vishnu came as a Matsya (fish) to save Sage Manu from the floods that covered the Earth and to recover the Vedas from a demon’s hands. After that the Devas (gods of heaven) discovered that the divine nectar of immortality had been lost and it was at the bottom of the sea. Lord Vishnu helped in its recovery by becoming a Kurma (tortoise) to support a huge mountain on His back that was used as a churning rod to remake the nectar.
Lord Vishnu took the Avatar of Varaha (boar) to kill a demon named Hiranyaksha, who dragged the Earth to the bottom of the ocean. Lord Vishnu, after killing the demon, then brought the Earth back from the bottom of the ocean. After the death of Hiranyaksha, his twin-brother Hiranyakasipu became the king of demons. He made everyone treat him as God. Since Hiranyakasipu had received a boon from Lord Brahma that he could not be killed by either a man or an animal, Lord Vishnu took the form of a Narasimha (man-lion) and killed him.
Lord Vishnu came as Vamana (the dwarf) to get rid of the pride of the demon-king Mahabali. Unlike any other demon, Mahabali was a very good king. During the reign of Mahabali, the world was like heaven and everyone was praising him in the three worlds. Lord Vishnu came down as Vamana and made Mahabali promise him that area of land which he could cover in three small steps. Mahabali agreed. Then Vamana immediately became a giant and took two steps that covered all the three worlds.
His second step even punctured the covering of the universal shell and let in a drop of the spiritual Karana Ocean. . . which fell through the heavens and onto the Earth and became the Ganges River. He did not have a place to put his third step so Mahabali requested him to place his third step on his head.
Then Vamana pushed Mahabali to the third world known as Patala. People in Kerala still celebrate the reign of Mahabali by a celebration named Onam. Lord Vishnu also came as Parasurama (the warrior with an axe) to save the world from the tyranny of the evil Kshatriyas. Then He came as Rama, to annihilate the demon king of Lanka, as described in the Ramayana. The incarnation of Lord Vishnu as Krishna is the most popular avatara of all. There are many pastime stories of Lord Krishna. Hindus also consider the Buddha as an avatara. Kalki (man on white horse), as I said before, is an avatara yet to come to restore the Earth’s purity. You should read Srimad-Bhagavata to get all details of these avataras.
With other incarnations of Lord Vishnu, according to the Bhagavata Purana, the main avatars number twenty-two. They consist of the ten incarnations already described and 12 more as follows: 1. Sanat Kumara and his three brothers; 2. Sage Narada (exponent of Bhakti and Tantras): 3. Saints Nara and Narayana; 4. Sage Kapila (founder of the Samkhya System); 5. Dattatreya (the greatest magician who restored Vedic rites); 6. Yajna (Lord Vishnu as identified as the sacrifice); 7. Rishabha (founder of the pre-Aryan Jain philosophy); 8. King Prithu; 9. Dhanvatari, the founder of Ayurveda, (he came from the ocean of milk, holding the divine elixir; Amrith); 10. Balarama (came as brother of Lord Krishna, he is an embodiment of virtues); 11. Sage Veda Vyasa (author of the Vedas, Vedanta Sutras, and Mahabharata and the Bhagavatam); 12.Mohini (the Lord’s feminine incarnation) who deprived the demons of the divine elixir, Amrith. There are still more Avatars of Lord Vishnu which are not mentioned in the list above