All Souls' Day, observed on November 2, is a Catholic day of prayer and remembrance for the souls of all the faithful departed. Rooted in early Christian tradition, it was formally established in the 10th century by Abbot Odilo of Cluny, who dedicated the day for praying for souls in Purgatory to help them reach heaven. Catholics believe that prayers, Masses, and sacrifices offered on All Souls' Day aid in the purification of these souls.

Many observe the day by attending Mass, visiting cemeteries, lighting candles, and offering prayers for deceased loved ones. This commemoration follows All Saints' Day and forms part of the Hallowtide triduum, emphasizing both the communion of saints and the hope of eternal life.