Hallowe'en has its origins in ancient Celtic traditions from the festival of Samhain. It was celebrated on October 31st and involved rituals, costumes, and predicting the future. Over time, Christian traditions replaced pagan ones and All Hallow's Eve evolved into Hallowe'en. Modern Hallowe'en traditions include wearing costumes to school parties, carving jack-o'-lanterns, trick-or-treating, and teenagers having costume parties in the evening. Irish immigrants brought trick-or-treating to America in the 19th century, where children now go door-to-door in costumes asking for treats.