Diwali, also known as the festival of lights, is the biggest festival celebrated by Hindus, Sikhs and Buddhists around the world.

Its date changes every year and commemorates different things depending on local tradition and culture.

When is Diwali?

As per India's official holiday calendar, Diwali in 2017 will be on October 19, coinciding with the 15th day of Kartik, the holiest month in the Hindu lunar calendar.

In southern India and in Singapore, Diwali will be observed on October 18, which is also an official holiday in Malaysia, Myanmar, Nepal, Sri Lanka and the Sindh province in Pakistan.

In the Gregorian calendar, the Diwali festival always falls between mid-October and mid-November.

What does it commemorate?

Hindus celebrate the triumph of good over evil - of light over darkness - to mark the return of Ram, the lord of virtue, to his kingdom after 14 years of exile.

Followers of Jainism commemorate Mahavira, a venerated ascetic who fundamentally reformed the faith, reaching a state of nirvana after his death.

Sikhs use Diwali to mark the anniversary of the release from prison of Guru Hargobind in 1619.

For Buddhists, this day represents the time Emperor Ashoka gave up everything and adopted a path of peace after going through bloodshed and death. The day is observed as Ashok Vijayadashami.

How is it celebrated?

Traditional earthen diyas or candles are lit, and nowadays, fireworks are set off.

Houses are cleaned and decorated with colourful rangoli artworks - patterns created on the floor using coloured rice or powder.