Krishna is considered to be the avatar of Vishnu the Preserver, one of the triumvirate of the Hindu trinity of gods.
The Festival of Lights moniker, as you might guess, comes from the decorative lights and oil lamps, called diyas, that people hang during the holiday.
How people celebrate Diwali How people observe Diwali is as diverse as the people who celebrate it itself, though the classic theme of light conquering darkness and knowledge over ignorance runs through all celebrations.