"An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints." (Catechism of the Catholic Church §1471)
Indulgences can be applied either to oneself or to the souls of the deceased, but they cannot be applied to other persons living on earth.
How it works: On All Souls’ Day (Nov 2nd) a plenary indulgence, applicable only to the Poor Souls in Purgatory, is granted to those who visit a Catholic church and there recite one Our Father and one Creed.
On all the days from November 1st through November 8th inclusive, a plenary indulgence, applicable only to the Poor Souls in Purgatory, is granted to those who visit a cemetery and pray even if only mentally for the departed. There must be one visit for each day one seeks to gain the indulgence; one visit will not apply for several days. Any public cemetery with Christian tombs will do. The nearest one to St Mary's Shrine is five minutes walk away: St Elphin’s, Church Street, WA1 2TL.
Conditions for all these indulgences:
1. Only one plenary indulgence can be granted per day. 2. It is necessary to be in the state of grace, at least by completion of the work. 3. Freedom from attachment to sin, even venial sin, is necessary; otherwise the indulgence is only partial. (By this is meant attachment to a particular sin, not sin in general.) 4. Holy Communion must be received each time the indulgence is sought. 5. Prayers must be recited for the intentions of the Holy Father on each day the indulgence is sought. No particular prayers are prescribed. One Our Father and one Hail Mary suffice, or other suitable prayers. 6. One must be absolved in confession the week before or following. (One confession made during the week, made with the intention of gaining all the indulgences, suffices.)