New Delhi, Oct. 27 -- Halloween, observed every October 31, is one of the most popular holidays in the United States, known for costumes, trick-or-treating, and festive decorations. Children and adults alike enjoy dressing up as ghosts, witches, vampires, and pumpkins, and participating in parties and community events.

Ancient origins: Halloween traces back over 2,000 years to the Celtic festival of Samhain in what is now Ireland, the UK, and northern France. The Celts celebrated the end of the harvest season on October 31, believing the boundary between the living and the dead was blurred, allowing spirits to roam the earth.

Roman influence: After the Romans conquered Celtic lands, two Roman festivals merged with Samhain: Feralia, hono...