Halloween is a holiday celebrated each year on October 31, and Halloween 2024 will occur on Thursday, October 31.In the eighth century, Pope Gregory III designated November 1 as a time to honor all saints.Over time, Halloween evolved into a day of activities like trick-or-treating, carving jack-o-lanterns, festive gatherings, donning costumes and eating treats.Soon, All Saints Day incorporated some of the traditions of Samhain.