Halloween traditions date back to the ancient Celts who celebrated Samhain 2000 years ago on November 1st to mark the start of winter. They had big parties with food, bonfires, dancing and singing to say goodbye to the sun and welcome ghosts of the dead. The modern Halloween incorporates aspects of the Celtic Samhain celebration as well as the Christian All Saints' Day, with traditions like carving pumpkins, dressing in costumes, and trick-or-treating.