The Trimurti is a concept in Hinduism in which the cosmic functions of creation, maintenance, and destruction are personified by the forms of Brahma the creator, Lord Vishnu the maintainer or preserver, and Lord Shiva the destroyer or transformer. These three deities have been called the Hindu triad or the "Great Trinity". Of the three members of the Trimurti, the Bhagavad Purana, which espouses the Vaishnavite viewpoint, explains that Lord Vishnu is the supreme deity.
Vishnu is the Lord of protection, sustenance & maintenance. His consort Goddess Lakshmi is the possessor of wealth, which is a necessity for maintenance. Goddess Lakshmi represents not only material wealth, but the wealth of grains, beauty, courage, valour, offspring, success, luxurious life, eternal bliss. Vishnu and Lakshmi thus help the souls introduced into the life cycle by Brahma to survive in the cycle of life.
In the Puranas, Lord Vishnu is described as having the divine colour of water filled clouds, four-armed, holding a lotus, gada (mace), shankha (conch) and chakra (wheel). Lord Vishnu is also called Neelameghashyamala - possessing a complexion the colour of the dark clouds. Vishnu is also described in the Bhagavad Gita as having a 'Universal Form' (Vishvarupa) which is beyond the ordinary limits of human perception or imagination. His vahana is Garuda.
He rests on the ocean on his bed of Adisesha (serpent with 1,000 heads). Any time Lord Vishnu sees great trouble, He takes an avatar to rescue the people from evils. He is all merciful, ever rushing to protect his devotees.
In almost all Hindu denominations, Lord Vishnu is either worshipped directly or in the form of his ten avatars (dashavtar), most famous of whom are Rama and Krishna. The Bhagavad Gita mentions their purpose as being to rejuvenate Dharma and vanquish negative forces, the forces of evil that threaten Sanatan Dharma, as also to display His divine nature in front of the fallen souls.
The following prayer has been extracted from Gajendra Moksha Stotram-18th stanza, which occurs in the eighth Skanda and third chapter of Bhagwatha Purana (Sloka 2-29).
Whosoever prays to You for dharma, desire, wealth or salvation,
They get their desires fulfilled, and even when Your devotees,
Do not ask anything from You, You give them an imperishable body,
And I request from You salvation for me.