Diwali, or Deepavali, is the best known festival in the Hindu year, celebrated with rows of oil lamps, rangoli, family meals and the worship of Lakshmi, the goddess of prosperity. For many communities it also recalls Rama's homecoming to Ayodhya after fourteen years of exile.
The main night falls on the new-moon day (Amavasya) of the month of Kartika in the Purnimanta reckoning, which is the Amavasya ending the month of Ashwina in the Amanta system used in western and southern India. The Lakshmi Puja is timed to the pradosh period, the stretch just after sunset while Amavasya is still running, so the exact muhurta changes with local sunset.
Regional practice varies widely: in much of the north Diwali is the calendar's turn of the year and is preceded by Dhanteras and followed by Govardhan Puja and Bhai Dooj, while in Bengal the same night is kept as Kali Puja.