Millions of Indians celebrate Diwali, the festival of lights and one of the most important events in the Hindu calendar.

The annual festival usually takes place between October and November, but the exact date varies each year as the Hindu calendar is based on the moon.

This year Diwali will be celebrated on Thursday, but in some parts of the country the festival will also be celebrated on Friday.

On this day, people light oil lamps and candles to symbolize the triumph of light over darkness and good over evil.

Ahead of Diwali, people clean and organize their homes. New clothes are bought and sweets and gifts are exchanged with friends, families and neighbors.

Many pull traditional designs like rangoli – made with colorful powders – outside their doors to welcome good luck and positivity.

On this day, families worship Lakshmi, the Hindu goddess of wealth.

Lamps are lit and windows and doors are left open to help the goddess find her way into people's homes.

Fireworks are also an important part of the celebrations, but in recent years several state governments have restricted or banned the practice as northern Indian states struggle with severe air pollution.

During the festival, the capital Delhi has a complete ban on the sale and use of firecrackers, while in states such as Haryana, Punjab and Karnataka, the use of firecrackers is restricted to certain hours on Diwali evening.