1) The Christian All Souls' Day holiday, sometimes called Day of the Dead, immediately follows All Saints' Day on Nov. 2 every year. However if the day falls on a Sunday, it is celebrated on Nov. 3.

2) While All Saints' Day honors saints and martyrs, All Souls' Day honors all others who have passed away.

3) The holiday is a time for the living to pray for those souls that may still be in purgatory—a place where souls are purified before they move on to Heaven. This is based on the belief that upon death, souls are not totally cleansed of sin and need to suffer in purgatory before moving on.

4) All Souls' Day stems from the Pagan Festival of the Dead, which celebrated the Pagan belief that the souls of the dead would return for a meal with the family.

5) The day was orginally celebrated during the Easter season.

Sources: 123Holiday.net and New Advent Catholic Encyclopedia

If you are looking to celebrate the holiday, see Richfield Patch's list of mass times and dates.