Diwali — Deepavali, the 'row of lamps' — is the most pan-Indian of Hindu festivals. Three principal stories converge on the same night. In the Vaishnava reading, the day commemorates the return of Lord Rama to Ayodhya after his fourteen-year exile and victory over Ravana; the citizens of Ayodhya lit oil lamps in every doorway to guide him home. In the Shakta reading, the night honours the killing of the demon Narakasura by Krishna and Satyabhama. In the most widely-observed household reading, Diwali is the night Goddess Lakshmi — the goddess of wealth, prosperity, and beauty — walks the earth and enters every house she finds clean, lit, and ready to receive her.

The five-day sequence threads through the lunar calendar: Dhanteras (the 13th of the dark fortnight of Kartika), Naraka Chaturdashi or Choti Diwali (the 14th), Lakshmi Puja or Diwali proper (Amavasya, the new moon), Govardhan Puja (the first of the bright fortnight), and Bhai Dooj (the second). The Amavasya night is the darkest of the lunar month — which is precisely why lamps matter.

Houses are cleaned and decorated in the days leading up to Diwali — dusting that has accumulated through the year is finished, rangolis are drawn at the threshold, and the doorway is decorated with marigold and mango leaves. Lakshmi will not enter a home that is dirty, dark, or contentious.

On Diwali night, families perform Lakshmi-Ganesha puja — Ganesha for removing obstacles, Lakshmi for blessing wealth. New clothes are worn, business books are opened (the start of the Vikram Samvat fiscal year for many traders), sweets are exchanged, and lamps are lit at every threshold and window. Firecrackers — increasingly substituted with safer alternatives — wake the night.