Dhanteras, also called Dhantrayodashi, is the first day of the five-day Diwali sequence. Households clean and decorate the home, light the first lamps, and many people buy gold, silver or new utensils because metal acquired on this day is held to bring lasting prosperity. The evening worship is directed to Lakshmi and to Kubera, and a lamp is often set outside the door for Yama.
The day is the thirteenth tithi (Trayodashi) of the waning fortnight of Kartika in the Purnimanta calendar, falling two days before the Diwali new moon. The buying and puja muhurta is usually reckoned during the pradosh window after sunset, so its clock time depends on the city.
Dhanteras is also observed as the birthday of Dhanvantari, the physician of the gods, and is marked by practitioners of Ayurveda as a day of medicine and healing.