The celebration marks the day before the Western Christian feast of All Saints and initiates the season of Allhallowtide, which lasts three days and concludes with All Souls’ Day.

The tradition originated with the ancient Celtic festival of Samhain when people would light bonfires and wear costumes to ward off ghosts. In the eighth century, Pope Gregory III designated November 1 as a time to honor all saints. Soon, All Saints Day incorporated some of the traditions of Samhain.