All Hallow's Eve is the original name for Halloween and occurs on October 31. It was originally observed as the night before the Roman Catholic holiday All Hallow's Day, which honors the saints. Over time, All Hallow's Eve developed into the secular Halloween.
All Hallow's Eve originated in the eighth century when Pope Gregory III chose November 1 as the day to remember the saints, which eventually became All Saints' Day. Some believe that All Hallow's Eve may have originated earlier as the ancient Celtic festival of Samhain. Early customs included going door to door to offer prayers for the dead in exchange for treats and lighting bonfires. Halloween began developing as a secular holiday in the United States in the 1800s when it became more focused on community parties than religion.