"All Souls Day was started in 998. It’s a Roman Catholic day of remembrance for friends and loved ones who have passed away. All Souls Day is on November 2, following All Saints Day.
November 2 is the day on which special prayers are offered for the souls of the faithful which at death have not been cleansed from venial sins, or have not atoned for past transgressions, cannot attain beatific vision. It is a time to pray for their souls to assist the souls from Purgatory to Heaven.
The Day of the Dead, All Souls Day, is an official holiday of the Catholic Calendar. On this day, three requiem masses are celebrated: one for the celebrant, one for the departed, and one for the pope."