Halloween has its origins in ancient festivals celebrated by cultures like the Romans and Celts. Celebrated on October 31st, Halloween is thought to be the one night when ghosts, witches, and fairies are most active. Traditions like carving jack-o'-lanterns, bobbing for apples, dressing up in costumes, and kids saying "trick or treat" as they receive candy and snacks have been influenced over time from various holidays and cultures.