Halloween, also known as All Hallows' Eve, is a holiday observed on October 31st. Its origins can be traced back to the ancient Celtic festival of Samhain, which marked the end of the harvest season and the beginning of winter. The Celts believed that on this night, the boundary between the living and the dead became blurred, allowing ghosts and spirits to roam freely.

To ward off these spirits, the Celts would light bonfires and wear costumes and masks. They also believed that the spirits could provide insights into the future, so they would often consult with Druids, who acted as intermediaries between the living and the dead.

When Christianity began to spread throughout Europe, the holiday of Samhain was merged with the Christian holiday of All Saints' Day, which was observed on November 1st. The evening before All Saints' Day became known as All Hallows' Eve, and eventually Halloween.

Over time, Halloween has evolved into a secular holiday that is celebrated with costumes, decorations, and trick-or-treating. Despite its modern-day commercialization, the holiday still retains its spiritual roots and continues to be celebrated by people around the world.