Wikipedia says : Holi, or Holli, also called the Festival of Colors, is a spring festival celebrated by Hindus, Buddhists, Sikhs and others. It is primarily observed in India, Nepal, Sri Lanka,[1] and countries with large Indic diaspora populations, such as Suriname, Guyana, South Africa, Trinidad, United Kingdom, United States, Mauritius, and Fiji.
Now let me tell you something, wikipedia says way too much. Go up north and you'd know what holi is.