Halloween originated from the ancient Celtic festival of Samhain, celebrated on October 31st. The Celts believed this was when the boundary between the living and the dead was at its thinnest. They would light bonfires and wear costumes to ward off ghosts. In the 9th century, the Catholic Church designated November 1st as All Saints' Day and made it a holy day of obligation. Halloween traditions include trick-or-treating, carving jack-o'-lanterns from pumpkins, wearing costumes, telling scary stories, and bobbing for apples. Today, Halloween is celebrated in many Western cultures with children going door-to-door looking for treats.