All Souls' Day, also known as the Commemoration of All the Faithful Departed and the Day of the Dead, is a day of prayer and remembrance for the souls of those who have died, which is observed by some Christian denominations. All Souls' Day is often, although not exclusively, celebrated in Western Christianity; Saturday of Souls is a related tradition more frequently observed in Eastern Christianity. Practitioners of All Souls' Day traditions often remember deceased loved ones in various ways on the day. Beliefs and practices associated with All Souls' Day vary widely among Christian churches and denominations.
In contemporary Western Christianity the annual celebration is held on 2 November, and is part of the season of Allhallowtide that includes All Saints' Day and its eve, Halloween. Prior to the standardization of Catholic observance on 2 November by St. Odlio of Cluny during the 10th century, many Catholic congregations celebrated All Souls Day on various dates during the Easter season as it is still observed in some Eastern Orthodox Church and Eastern Catholic Churches.