Vishnu is a Hindu god, the Supreme God of Vaishnavism (one of the three principal denominations of Hinduism) and one of the three supreme deities (Trimurti) of Hinduism. He is also known as Narayana and Hari. As one of the five primary forms of God in the Smarta tradition, he is conceived as "the Preserver or the Protector" within the Trimurti, the Hindu Trinity of the divinity.
Vishnu is one of the most important gods in the Hindu pantheon and, along with Brahma and Shiva, is considered a member of the holy trinity (trimurti) of Hinduism. He is the most important god of Vaishnavism, the largest Hindu sect. Indeed, to illustrate Vishnu’s superior status, Brahma is, in some accounts, considered to have been born from a lotus flower which grew from Vishnu’s naval. A complex character, Vishnu is the Preserver and guardian of men (Narayana), he protects the order of things (dharma) and, when necessary, he appears on earth in various incarnations or avatars to fight demons and fierce creatures and so maintain cosmic harmony.
Vishnu represents Sattvaguna and is the centripetal force as it were, responsible for sustenance, protection and maintenance of the created universe.
Etymologically speaking, the word 'Vishnu ' means 'one who pervades, one who has entered into everything. ' So he is the transcendent as well the immanent reality of the universe. He is the inner cause and power by which things exist.
Vishnu was married to Lakshmi (the goddess of good