The word "penance," can have a wide variety of meanings. One of the primary ways "penance" is used is in the sacrament of Penance.
For example, a priest will often give the penitent a penance, such as praying three Our Fathers or three Hail Marys.
The Catechism of the Catholic Church explains that this type of penance is meant to repair the damage done by our sins:
Many sins wrong our neighbor. One must do what is possible in order to repair the harm (e.g., return stolen goods, restore the reputation of someone slandered, pay compensation for injuries). Simple justice requires as much. But sin also injures and weakens the sinner himself, as well as his relationships with God and neighbor. Absolution takes away sin, but it does not remedy all the disorders sin has caused. Raised up from sin, the sinner must still recover his full spiritual health by doing something more to make amends for the sin: he must "make satisfaction for" or "expiate" his sins. This satisfaction is also called "penance."
Connected to this definition of penance is the "virtue of penance."
Virtue of penance
While this type of penance makes it possible to repair the damage done by our personal sins, we can also perform penance for other people's sins.
St. John XXIII referred to this type of penance in his encyclical, Paenitentiam Agere:
[T]he faithful must also be encouraged to do outward acts of penance, both to keep their bodies under the strict control of reason and faith, and to make amends for their own and other people's sins.
This means we can offer a variety of exterior practices as an act of penance to atone for the sins of others.
The Catechism of the Catholic Church provides a few examples:
[It] can consist of prayer, an offering, works of mercy, service of neighbor, voluntary self-denial, sacrifices, and above all the patient acceptance of the cross we must bear. Such penances help configure us to Christ, who alone expiated our sins once for all. They allow us to become co-heirs with the risen Christ, "provided we suffer with him."
This type of penance unites our suffering to the suffering of Jesus Christ on the cross, who offered the ultimate form of penance.
We can perform penance for any variety of prayer intentions, and God looks kindly upon our prayers and sacrifices done for other people.
