Diwali (or Deepavali, the  festival of lights ) is an ancient Hindu festival celebrated in autumn (northern hemisphere) every year. Diwali is the biggest and the brightest festival in India.iwali is also a festival of sounds and sights with fireworks and rangoli designs; the festival is a major celebration of flavors with feasts and numerous mithai (sweets, desserts), as well as a festival of emotions where Diwali ritually brings family and friends together every year.