Halloween is celebrated on October 31st and involves carving pumpkins, dressing in costumes, and children going trick-or-treating by visiting homes and saying "Trick or treat" to receive candies. The holiday originated from the Celtic tradition of Samhain where they believed the spirits of the dead would come back to life and many modern Halloween traditions such as costumes, jack-o-lanterns, and trick-or-treating derive from this ancient Celtic celebration.