Diwali is a 5-day festival celebrated in India to mark the triumph of good over evil and new beginnings. It is celebrated with lights, fireworks, and decorations to welcome the Hindu New Year. People light lamps outside their homes, give gifts, enjoy meals together, and participate in activities like making rangoli patterns or sweets. The festival originated from different harvest celebrations and stories depending on the region, such as commemorating the return of King Rama.