The origins of Halloween go back to the ancient Celts. The two important festivals on the Celtic calendar were Samhain and Beltane. Samhain marked the end of summer and the harvest season, and was considered the Celtic New Year. October 31st was an important date for the Druids, who would make fires and predict the future. The Celts would dress in costumes and play games to frighten away spirits. Halloween traditions were later influenced by the Romans and Christians. Today, Halloween is celebrated in the U.S. with costumes, parties, and trick-or-treating.