What to Know About Diwali, the Hindu Festival of Lights

India is shimmering.

This week is Diwali, the Hindu festival of lights and the biggest public holiday in the world’s most populous country. It’s a sensory overload of sweets, fireworks, oil lamps and flower garlands.

Diwali typically falls in October or November and lasts for several days. For millions of families across India and the Indian diaspora, it’s a time for feasting, self-reflection, and prayers for good fortune.

Here’s what to know:

The very basics, please.

Diwali is celebrated by Hindus and people of other faiths, including Jainism and Sikhism, and it generally symbolizes the triumph of good over evil — or light over darkness. People clean, celebrate and wish for prosperity.

The holiday draws on a range of ancient Hindu narratives.

Many North Indian families celebrate a part of the Ramayana epic, in which a royal protagonist, Rama, with help from a monkey god named Hanuman, vanquishes a demon who stole Sita, his princess.

In South India, people often celebrate Diwali by citing another Hindu epic, the Mahabharata, in which the god Krishna defeats a demon king.

When and where is Diwali celebrated?

Diwali falls on an auspicious day in the Hindu calendar: the new moon in the lunar month of Kartik. In 2025, that special moon day straddles Oct. 20 and Oct. 21.

The holiday is widely celebrated in other parts of South Asia, including Sri Lanka and Nepal, and it’s popular across the Indian diaspora. It also marks the start of the Hindu new year for many.

Tell me about those sweets.

A splash of background first.

Diwali rituals celebrate several Hindu gods and goddesses overcoming evil forces. They include Lakshmi, the goddess of prosperity; Ganesh, the elephant-headed god of good fortune and remover of obstacles; and Kali, a ferocious goddess who wears a necklace of skulls.

The rituals unfold over several days and include pujas, or ceremonies, in which people light lamps and make offerings to the gods. People also deep-clean their homes buy new goods for their households.

The offerings can include incense, garlands of jasmine and marigolds and a range of extremely sugary treats. The thinking goes that the offerings boost one’s chances of attaining material riches and spiritual enlightenment.

What about fireworks?

People across India typically light firecrackers to ring in Diwali. Even young children go outside to wave sparklers in streets, parks and backyards.

All that color looks great, but the fumes and smoke are bad for air quality — during a time of year when India’s air tends to be unhealthy in the first place.

Last week, India’s Supreme Court relaxed a blanket ban on fireworks in the capital, New Delhi, by allowing the sale of so-called green fireworks for a few days at the beginning of Diwali. But experts predicted that Delhi’s air would be as unhealthy as ever during the holiday.

So far, they’re right. On Monday afternoon, a few hours into the start of the final day of Diwali, the authorities declared that the air quality in Delhi had reached officially hazardous levels.

Anupreeta Das and Suhasini Raj contributed reporting.