how did halloween originate

Halloween originated from the ancient Celtic festival of Samhain, which was celebrated around November 1st as a marking of the end of the harvest season and the beginning of winter. The Celts believed that on the night before this date, the boundary between the living world and the dead was thin, allowing spirits to return to the earth. To ward off these spirits, people would light bonfires and wear costumes. In the 8th century, Pope Gregory III designated November 1 as All Saints Day to honor saints, which incorporated some of the Samhain traditions, with the evening before becoming known as All Hallows Eve, eventually shortened to Halloween. Halloween traditions brought to America by European immigrants evolved into the day of festive activities now known as trick-or-treating, costume wearing, and pumpkin carving. The holiday combines pagan roots, Christian influences, and folk customs over centuries.