The Bible tells us that "It is therefore a holy and wholesome thought to pray for the dead, that they may be loosed from sins" (2 Maccabees 12:46), and especially in the month of November, the Catholic Church urges us to spend time in prayer for those who have gone before us.
The Church offers a special plenary indulgence, applicable only to the souls in Purgatory, on All Souls Day (November 2), but She also encourages us in a special way to continue to keep the Holy Souls in our prayers throughout the first week of November. The Church offers an Indulgence for a Cemetery Visit that is available as a partial indulgence all year round, but from November 1 through November 8, this indulgence is plenary. Like the All Souls Day indulgence, it is applicable only to the souls in Purgatory. As a plenary indulgence, it remits all punishment due to sin, which means that simply by performing the requirements of the indulgence, you can obtain the entrance into Heaven of a soul who is currently suffering in Purgatory.
For most of us, the indulgence for a cemetery visit takes only a few minutes, and yet it reaps immense spiritual benefit for the Holy Souls in Purgatory--and for us as well, since those souls whose suffering we ease will pray for us when they enter into Heaven.
By Scott P. Richert, About.com Guide