Another name for Halloween is All Hallows' Eve. All Hallows' Eve means the day before All Hallows Day, a Catholic holiday that is more commonly known as All Saints Day.
Halloween was originally spelled Hallowe'en, as it is a contraction of All Hallows' Evening. All Hallows' Day occurs on Nov. 1 each year, giving Halloween its recurring date of Oct. 31. All Hallows' Day is a holiday that calls for prayer and remembers Catholic saints.
During medieval times, Halloween souling was commonly practiced, an activity where people would go neighbor-to-neighbor exchanging prayers for treats. This is similar to the trick-or-treating activity practiced in modern times.