Dhanteras is the worship of lord Dhanvantari.According to a popular legend, when the devas and asuras performed the Samudra manthan (churning of the ocean) for Amrita (the divine nectar of immortality), Dhanvantari (the physician of the Gods and an incarnation of Vishnu) emerged carrying a jar of the elixir on the day of Dhanteras. Lord Dhanvantari, according to Hindu traditions, emerged during Samudra Manthan, holding a Kalasha full of Amrit (an Ayurvedic herbal mix bestowing immortality) in one hand and the sacred text about Ayurveda in the other hand. He is considered to be the Vaidya of Gods.
On Dhanteras, homes that have not yet been cleaned in preparation for Diwali are thoroughly cleansed and whitewashed, and Lord Dhanvantari, the god of health and Ayurveda, is worshiped in the evening.
The main entrance is decorated with colorful lanterns, holiday lights and traditional motifs of Rangoli designs are made to welcome the Goddess of Wealth and Prosperity. To indicate her long-awaited arrival, small footprints are drawn with rice flour and vermilion powder all over the house. On the night of Dhanteras, diyas (lamps) are ritually kept burning all through the night in honor of Lakshmi and Dhanvantari.
Hindus consider this an extremely auspicious day for making new purchases, especially of gold or silver articles and new utensils. It is believed that new "Dhan" (wealth) or some item made of precious metal is a sign of good luck. In modern times, Dhanteras has come to be known as the most auspicious occasion for buying gold, silver, and other metals, especially kitchenware. The day also sees heavy purchases of appliances and automobiles.
On this night, the lights are set out every night both in the sky lamps and as offerings at the base of a Tulsi plant and also in the form of diyas, which are placed in front of the doorways of homes. This light is an offering to Yama, the Host of Death, to avert untimely death during the time of the Diwali festival. This day is a celebration aimed at increasing wealth and prosperity. Dhanteras engages themes of cleansing, renewal, and the securing of auspiciousness as embodied by Lakshmi.