In Rigveda, Vishnu is not a very prominent god. He is one of the Adityas—sons of Aditi, the mother of gods. He is associated with Sun and Fire, who are major gods. Vishnu is the god of grace. He welcomes the faithful worshippers of the gods to heaven. He is the creator of the solar year. Vishnu gained more prominence in the later Vedas like Yajurveda. He became known as the preserver who sleeps on the coils of the world-serpent, Shesha. The many hoods of Shesha form a protective canopy over Vishnu.
Shesha rests on Kurma—the tortoise, who is also a form of Vishnu. When Kurma moves its limbs, Shesha is roused to yawn. This is believed to cause earthquakes. The Greek ambassador Megasthenes, who resided in India between BC 311 and 302, wrote that Herakles must be the same as Vishnu and his incarnation Krishna.
At the dawn of each new Yuga (age), Vishnu awakes from his cosmic sleep in the ksheer-sagara or ocean of milk. He gives rise to Brahma, who then proceeds to create the universe. In most Hindu creation myths, Vishnu is the first among gods, who give rise to the other gods.
Vishnu is blue or black in complexion. He resides in Vaikuntha. His vehicle is Garuda—the eagle. He is four-armed. In his arms, he holds a shankha (conch shell), which is used to produce an auspicious sound at the start of a ceremony; a chakra (discus), his chief weapon, which can cut off the heads of his enemies and return back to Vishnu; a Gada (club), a symbol of knowledge and power; and a Padma (lotus), the sacred flower associated with the beginning of the universe.
Among the trinity, Vishnu has the distinction of having the most avatars. Two of the greatest epics of India, Ramayana and Mahabharata, are about avatars of Vishnu—Rama and Krishna. There are believed to have been 10 major incarnations of Vishnu. Besides Rama and Krishna, they were Matsya (the fish-man); Kurma (the tortoise-man); Varaha (the wild boar); Narasimha (the half-lion half-man); Vamana (the dwarf man); Parshurama; and Gautam Buddha. Many local deities are also linked to Vishnu.
For example, Jagannath, who has a strong following in Odisha and its surrounding areas, is also considered an avatar of Vishnu. The 10th avatar of Vishnu is believed to be Kalki who will appear at the end of Kali yuga, which is going on at present. He will be riding a white horse and, in his hand, he will hold a flaming sword. He will end the Kali yuga to begin the Krita yuga and another cycle of the four
yugas will start.