Every year, as autumn sets in, millions of homes across the world begin to light up with rows of small oil lamps, known as diyās. Neighbourhoods are filled with colourful decorations, streets come alive, families and friends get together, and sweets are shared. As night falls, fireworks light up the sky. This is Diwali, one of the widely celebrated festivals by Hindus, Jains, Sikhs and Buddhists.