Diwali, also called Deepavali or Dipavali, is the annual festival of lights celebrated by Hindus. Since it is a holiday, Diwali follows the standard rules of capitalization for proper nouns so it is capitalized.
What about “festival of lights?”
The phrase “festival of lights” is generally not capitalized unless used in a title.
For more title capitalization questions, use our free title capitalization tool here.