Halloween originated 2000 years ago in Celtic traditions where the Celts celebrated the end of the harvest season and the beginning of winter on November 1st, known as Samhain. They believed the night before, October 31st, was a time when the ghosts of the dead returned and people would wear costumes to disguise themselves from the ghosts. Over time, Christian holidays like All Saints' Day incorporated traditions from Samhain and Halloween evolved into a day of activities like trick-or-treating, carving jack-o-lanterns, and wearing costumes. Today, Halloween is celebrated as a time for costumes, parties, trick-or-treating, and eating candy.