People watch a laser show on the banks of the river Sarayu during Deepotsav celebrations on the eve of the Hindu festival of Diwali in Ayodhya on Wednesday. The five-day festival celebrates the victory of light over darkness.

Sanjay Kanojia/AFP via Getty Images

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People watch a laser show on the banks of the river Sarayu during Deepotsav celebrations on the eve of the Hindu festival of Diwali in Ayodhya on Wednesday. The five-day festival celebrates the victory of light over darkness.

Sanjay Kanojia/AFP via Getty Images

Hindus across the world are celebrating Diwali. The five-day festival of lights is one of the most popular holidays in India, and Thursday is the main day of festivities when faithful pray to the Hindu goddess of wealth.

People celebrate Diwali by lighting little earthen oil lamps to mark the victory of light over darkness.

What the holiday signifies

Diwali, or Dipawali, gets its name from the Sanskrit word “deepavali,” which means “row of clay lamps.” Many people in India will light these lamps outside of their homes to symbolize the inner light that protects them from spiritual darkness, in tune with a holiday that is an ode to the triumph of good over evil.

Hindu celebrations center around the return of Rama and Sita, two deities, to Ayodyha, an ancient city in India, after being exiled. Sikhs, Jains, and even Buddhists have their own lore surrounding the holiday — you can read about it here.

People light oil earthen lamps on the eve of Diwali at the Akshardham Hindu temple in Gandhinagar, India, on Wednesday.

Sam Panthaky/AFP via Getty Images

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People light oil earthen lamps on the eve of Diwali at the Akshardham Hindu temple in Gandhinagar, India, on Wednesday.

Sam Panthaky/AFP via Getty Images

The holiday overlaps with the Hindu New Year, and as a result is associated with a chance to reset and start anew.

The course of the five days includes cleaning house, buying new furnishings and exchanging gifts with loved ones. It also centers on traditions like buying new kitchen utensils to help bring good fortune, and other practices to attract the goodwill of spirits.

What the festivities look like in India

In the northern Indian temple town of Ayodhya, authorities lit about a million such lamps, along the banks of a river.

People light earthen lamps on the banks of the river Sarayu during Deepotsav celebrations on the eve of the Hindu festival of Diwali in Ayodhya.

Sanjay Kanojia/AFP via Getty Images

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Sanjay Kanojia/AFP via Getty Images

People light earthen lamps on the banks of the river Sarayu during Deepotsav celebrations on the eve of the Hindu festival of Diwali in Ayodhya.

Sanjay Kanojia/AFP via Getty Images

Ayodhya is believed to be the birthplace of the Hindu god Lord Ram, and Diwali is said to be the day he returned home after defeating a demon.

Across India, celebrations include fireworks and devotional music.

Laborers transport an idol of the Hindu goddess Kali to a place of worship on the eve of Diwali at Kumortuli, the traditional potters’ quarter in northern Kolkata on Wednesday.

Dibyangshu Sarkar/AFP via Getty Images

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Laborers transport an idol of the Hindu goddess Kali to a place of worship on the eve of Diwali at Kumortuli, the traditional potters’ quarter in northern Kolkata on Wednesday.

Dibyangshu Sarkar/AFP via Getty Images

But amid the festivities, there are also concerns about air pollution caused by Diwali firecrackers.

Already, pollution in the capital of New Delhi has risen to its worst this season.

Visitors walk along the Raisina Hills at Rajpath amid smoggy conditions in New Delhi on Thursday.

Sajjad Hussain/AFP via Getty Images

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Visitors walk along the Raisina Hills at Rajpath amid smoggy conditions in New Delhi on Thursday.

Sajjad Hussain/AFP via Getty Images

Sushmita Pathak reported from Mumbai; Manuela López Restrepo is based in Brooklyn.

Separate versions of this story appeared on the Morning Edition live blog.