Halloween has its origins in ancient Celtic harvest festivals that date back over 6,000 years. It was originally a pagan festival that marked the end of the Celtic calendar year and was a time to celebrate the harvest and remember loved ones who had passed away. Traditions such as wearing costumes and carving pumpkins evolved from ancient practices to ward off ghosts and pay tribute to deceased relatives. Today, Halloween is celebrated in many countries on October 31st with activities like trick-or-treating, carving jack-o-lanterns, wearing costumes, and attending parties.