Definition

• “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.”
• “An indulgence is obtained through the Church who, by virtue of the power of binding and loosing granted her by Christ Jesus, intervenes in favour of individual Christians and opens for them the treasury of the merits of Christ and the saints to obtain from the Father of mercies the remission of the temporal punishments due for their sins. Thus the Church does not want simply to come to the aid of these Christians, but also to spur them to works of devotion, penance, and charity.”

Explanation

• An indulgence is partial or plenary according as it removes either part or all of the temporal punishment due to sin. It may be applied to the living or the dead: through indulgences the faithful can obtain for themselves and also for the souls in purgatory-the remission of temporal punishment resulting from sin. Because we and the faithful departed now being purified are members of the same communion of saints, one way in which we can help them is to obtain indulgences for them, so that the temporal punishments due to their sins may be remitted.

Requirements 

Only one plenary indulgence, with the exception of the plenary indulgence applicable at the moment of death, may be gained on anyone day. Several plenary indulgences may be gained on the basis of a single sacramental confession; only one may be gained, however, on the basis of a single Communion and prayer for the pope’s intentions.
If we are not properly disposed to receive a plenary indulgence when it is granted to us, we receive only a partial indulgence, according to the degree of perfection of our dispositions.
To gain an indulgence one must:

• Be baptized, not excommunicated, and in the state of grace at least at time of completion of the prescribed works.
• Have at least the intention of receiving the indulgence and fulfill the enjoined works at the stated time and according to the tenor of the grant.

The usual conditions for gaining a plenary indulgence are, in addition to the good work to which it is attached:

• Confession and holy Communion on the day of the performance of the good work itself, or within a few days before or after.
• Prayer for the intentions of the pope. For this, recita­tion of one Our Father and one Hail Mary suffices, though the faithful may say any other prayer, according to their personal devotion.
• Exclusion of all attachment to sin, even the slightest venial sin.
• Reception of holy Communion and prayer for the pope’s intentions are should take place on the same day as the good work.

Plenary Indulgence 

One may gain a plenary indulgence by:

• Visiting the Blessed Sacrament for half an hour. • Visiting any parish church:

On the day of the titular feast of the church. On August 2, the day of the “Portiuncula indulgence,” or on another suitable day to be fixed by the local ordinary (usually the bishop.) On November 2 (applicable to the dead only).
On these visits one should recite the Our Father and the Creed and fulfill the three requirements (Confession, Communion, and prayer for the pope’s intentions).
•• Reading the Bible for at least half an hour. •• Making the Stations of the Cross.
•• Praying the Rosary (five decades) in a church or with one’s family .
•• Receiving the Apostolic Blessing at the hour of death.

Partial Indulgence 

One of the faithful who, being at least inwardly contrite, performs a work carrying with it a partial in­dulgence receives through the Church the remission of temporal punishment. A partial indulgence is granted to the faithful who:
•• In the performance of their duties and in bearing the trials of life raise their minds with humble confidence to God, adding-even if only mentally-some pious invocation. 
•• In a spirit of faith and mercy give of themselves or of their goods to serve others in need.

• In a spirit of penance voluntarily deprive themselves of what is licit and pleasing to them.
• Devoutly use religious articles (crucifixes, rosaries, scapulars, medals) properly blessed by a priest.