Vishnu is one of the principal deities of Hinduism and is known as The Preserver within the Trimurti, the triple deity of supreme divinity that includes Brahma and Shiva. He is the supreme being within Vaishnavism, one of the major traditions. Vishnu is the god of Preservation, the great maintainer who often appears in various incarnations (avatara) to provide salvation for humanity. He creates, protects, and transforms the universe. Vishnu is also revered along with Shiva and Brahma in the Shaktism tradition, where the Goddess, or Adi Shakti, is described as the supreme Para Brahman.
Vishnu is portrayed with having blue skin and four arms, and as dressed with extensive jewelry, flower garlands, a wrapped skirt, and a large crown. He is known chiefly through his avatars (incarnations), particularly The Hindu God Krishna, and Rama. Vishnu manifests a portion of himself anytime he is needed to fight evil to uphold the moral order, and his appearances are innumerable. Some of his best-known avatars, who are tremendously popular and beloved throughout Hindu India, are the gods Krishna and Rama.
In Hinduism, Vishnu is the second god in the Hindu triumvirate (or Trimurti) and is responsible for the preservation and protection of the universe. His role is to return to the earth in troubled times and restore the balance of good and evil. Vishnu is also associated with light and especially with the Sun. His distinguishing characteristic in the Vedas is his association with light.
In summary, Vishnu is the god of Preservation, the great maintainer who often appears in various incarnations to provide salvation for humanity. He is one of the principal deities of Hinduism and is responsible for the preservation and protection of the universe.