Halloween traces its origins back over 2,000 years to the ancient Celtic festival of Samhain, celebrated on October 31 to mark the end of the harvest season and the beginning of winter, a time associated with death and darkness. The Celts, who lived in areas that are now Ireland, the United Kingdom, and northern France, believed that on this night, the boundary between the living and the dead blurred, and spirits could roam the earth. People would light bonfires and wear costumes to ward off these wandering spirits and prevent them from causing harm.

As Christianity spread, pagan traditions were often adapted into Christian observances. By the 8th century, Pope Gregory III designated November 1 as All Saints’ Day, or All Hallows' Day, to honor saints and martyrs. The evening before became known as All Hallows' Eve, later shortened to Halloween. During this period, people continued to hold celebrations that included dressing in costumes, telling ghost stories, and lighting candles to guide souls back to their resting places.

When immigrants, particularly from Ireland and Scotland, came to North America in the 19th century, they brought Halloween traditions with them. The practice of “souling” in Europe, where poor people would go door-to-door offering prayers for the dead in exchange for food, evolved into the American custom of trick-or-treating. Similarly, the use of turnips as carved lanterns in Ireland was adapted to the now-iconic carved pumpkin, or “jack-o'-lantern,” in the U.S.

Halloween has since evolved into a largely secular holiday focused on fun and festivity, with traditions like costume parties, haunted houses, and trick-or-treating. However, its origins reflect a blend of ancient rituals and religious customs that sought to navigate the mysteries of life, death, and the supernatural.