Holi stands for Prahlada, the young bhakta who survived the tyranny of his father Hiranyakashipu thanks to Vishnu's protection. Holika, the tyrant's sister, was consumed by fire; Prahlada was untouched. The eve is called Holika Dahan, and the ash of the fire becomes a charm of luck.
The next morning everyone throws powder. Red, yellow, green, pink, blue. It stays three days on the skin, six days in the clothes, and a lifetime in the family album. We celebrate in the temple courtyard — wear something that can get dirty, and bring eye protection if you wear contact lenses.