Holi is a Hindu festival that celebrates spring, love, and new life. It also celebrate the Hindu god Krishna. This year, Holi begins March 29, but celebrations begin the night before.
After sundown, at the Holika Dahan, people gather to perform religious rituals in front of a bonfire, and to pray that their internal evil be destroyed the way Holika, the sister of the demon king Hiranyakashipu, was destroyed by fire. The next morning is celebrated as Rangwali Holi, a free-for-all festival of colors.
For more on this festival of colors, check out BBC Bitesize.