Explainer: What is Diwali and how is the festival celebrated?

Indians celebrate the bond of brothers and sisters in the Hindu festival Rakshabandhan

The dates of the festival are based on the Hindu lunisolar calendar, typically falling in late October or early November.

This year, the holiday starts on October 31 and November 1. Diwali falls on Halloween this year, and some celebrants have already been seen lighting tea lights called diyas in their scary costumes or handing out sweet treats like ladoos to trick-or-treaters.

While Diwali is a major religious festival for Hindus, it is also observed by Sikhs, Jains and Buddhists. The origin story of Diwali varies depending on the region. All these stories have one underlying theme – the victory of good over evil.

In southern India, Diwali celebrates the victory of Lord Krishna’s destruction of the demon Naraka, who is said to have imprisoned women and tormented his subjects. In northern India, Diwali honours the triumphant return of Lord Rama, his wife Sita, and brother Lakshmana from a 14-year exile in the forest.

The festival brings with it a number of unique traditions, which also vary by region. What all celebrations have in common are the lights, fireworks, feasting, new clothes and praying.

In southern India, many have an early morning warm oil bath to symbolise bathing in the holy River Ganges as a form of physical and spiritual purification.

In the north, worshipping the Goddess Lakshmi, who symbolises wealth and prosperity, tends to be the norm.

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Gambling is a popular tradition because of the belief that whoever gambled on Diwali night would prosper throughout the year. Many people buy gold on the first day of Diwali, known as Dhanteras – an act they believe will bring them good luck.

Setting off firecrackers is a cherished tradition, as is exchanging sweets and gifts among friends and family. Diwali celebrations typically feature rangoli, which are geometric, floral patterns drawn on the floor using colourful powders. This year, several northern Indian states, including the capital of New Delhi, are instituting partial or total fireworks bans to combat rising pollution levels during Diwali.

Buddhists, Jains and Sikhs have their own Diwali stories:

• Jains observe Diwali as the day the Lord Mahavira, the last of the great teachers, attained nirvana, which is liberation from the cycle of birth, death and rebirth.

• Sikhs celebrate Bandi Chhor Divas – a day that overlaps with Diwali – to commemorate the release of Guru Hargobind, a revered figure in the faith, who was imprisoned for 12 years by the Mughal emperor Jahangir.

• Buddhists observe the day as one when the Hindu Emperor Ashoka, who ruled in the third century BC, converted to Buddhism.

This year, Mattel released its “Barbie Signature Diwali Doll” by designer Anita Dongre, who wrote on Instagram that her Barbie represents “the fashion-forward modern woman who wears India on her sleeve with pride.”

In contrast to her earliest iteration in 1996, clad in a bright pink sari or the 2012 avatar packaged with a “monkey friend,” Diwali Barbie is fashionably dressed in a lehnga – an ankle-length embroidered skirt with motifs from Dongre’s home state of Rajasthan – a cropped blouse and vest.

This doll, priced at US$40 (HK$310), sold out on day one on Mattel’s website.