Final answer:
Halloween originated in ancient Celtic regions such as Ireland and the United Kingdom during the festival of Samhain, where people would wear costumes and light bonfires to ward off evil spirits.
Step-by-step explanation:
Halloween originated in the ancient Celtic festival of Samhain, which was celebrated in regions that are now modern-day Ireland, the United Kingdom, and parts of France. The festival marked the end of summer and the harvest season, and it was believed that the boundary between the living and the dead was blurred during this time. People would wear costumes and light bonfires to ward off evil spirits.
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