What is Dhanteras?
Dhanteras opens the five days of Diwali on the thirteenth of the waning moon in Kartik, honouring Dhanvantari, physician of the gods, and Lakshmi. It is dated by the evening Pradosh window rather than by sunrise.
How it is observed
Metal — gold, silver, or at minimum a steel vessel — is bought on this day for luck. Lamps are lit at the threshold and kept burning through the night.