Dhanvantari is an avatar of Vishnu in Hinduism. He appears in the Vedas and Puranas as the physician of the gods (devas), and the god of Ayurveda. It is common practice in Hinduism for worshipers to pray to Dhanvantari seeking his blessings for sound health for themselves and/or others, especially on Dhanteras.
Dhanvantari is a handsome individual and should usually be depicted with four hands, with one of them carrying Amrita, the ambrosia of god. Dhanvantari is depicted as Vishnu with four hands, holding Shankha, Chakra, Jalauka (leech) and a pot containing rejuvenating nectar called amrita. He is often shown with a leech in his hand rather than the scriptures
Bhagavata Purana states that Dhanvantari emerged from the Ocean of Milk and appeared with the pot of amrita (nectar) during the story of the Samudra (or) Sagara Mathana whilst the ocean was being churned by the Devas and Asuras, using the Mandara mountain and the serpent Vasuki. The pot of Amrita was snatched by the Asuras, and after this event another avatar, Mohini, appears and takes the nectar back from the Asuras. It is also believed that Dhanvantari promulgated the practise of Ayurveda.
His birthday is celebrated by the practitioners of Ayurveda every year, on Dhanteras, two days before Diwali, the Hindu festival of lights.
Lord Dhanvantari destroys negativity and blesses his devotees with good health.