Holi Phagwa is the Hindu festival of colors. It celebrates the coming of spring, fruitful harvests, unity, joy, and a tale from the Bhagavad Gita. It is traditional to celebrate by, among other things, throwing vibrantly colored powder (Holi Gulal) at one another. In addition to the throwing of colored powder it is traditional to light bonfires in celebration of the miraculous escape of a young devotee (Prahlada) of the god Vishnu. A demon (Holika) tried to throw him into a fire, but he escaped without any injuries due to his unshakable devotion.
One of Holi’s biggest customs is the loosening strictness of social structures, which normally include age, sex, status, and caste. Holi closes the wide gaps between social classes and brings Hindus together. Together, the rich and poor, women and men, enjoy each other’s presence on this joyous day. Additionally, Holi lowers the strictness of social norms. No one expects the decorum of normal life; as a result, the atmosphere is filled with excitement and joy.
We encourage you to learn as much as possible about this wonderful holiday and the stories/cultural underpinning behind it.
http://en.wikipedia.org/wiki/Holi is a good start, but their is a wealth of information to be had.