Penance (Reconciliation) is a Sacrament whereby the sins, whether mortal or venial, which we have committed after Baptism are forgiven.

The Sacrament of Penance increase the grace of God in the soul, besides forgiving sin; we should, therefore, often go to confession.

Our Lord instituted the Sacrament of Penance when he breathed on his Apostles and gave them power to forgive sins, saying: 'Whose sins you shall forgive, they are forgiven.' John 20:23

The priest forgives sins by the power of God, when he pronounces the words of absolution.

The words of absolution are: 'I absolve you from your sins, in the name of the Father, and of the Son, and of the Holy Spirit'.

Three conditions for forgiveness are required on the part of the penitent - Contrition, Confession, and Satisfaction.

Contrition is a hearty sorrow for our sins, because by them we have offended so good a God, together with a firm purpose of amendment. 

A firm purpose of amendment is a resolution to avoid, by the grace of God, not only sin, but also the dangerous occasions of sin.

We may obtain a hearty sorrow for our sins by earnestly praying for it, and by making use of such considerations as may lead us to it.

This consideration concerning God will lead us to sorrow for our sins: that by our sins we have offended God, who is infinitely good in himself and infinitely good to us.

This consideration concerning our Saviour will lead us to sorrow for our sins: that our Saviour died for our sins, and that those who sin grievously 'crucify again to themselves the Son of God, making him a mockery'. Heb. 6:6

Sorrow for our sins, because by them we have lost heaven and deserved hell, is sufficient when we go to confession.

Perfect contrition is sorrow for sin arising purely from the love of God.

Perfect contrition has this special value: that by it our sins are forgiven immediately, even before we confess them; but nevertheless, if they are serious, we are strictly bound to confess them afterwards.

Confession is to accuse ourselves of our sins to a priest approved by the Bishop.

If a person willfully conceals a serious sin in confession he is guilty of a great sacrilege, by telling a lie to the Holy Spirit in making a bad confession.

We have four things to do in order to prepare for confession:
first, we must heartily pray for grace to make a good confession;
secondly, we must carefully examine our conscience;
thirdly, we must take time and care to make a good act of contrition; and fourthly, we must resolve by the help of God to renounce our sins, and to begin a new life for the future.

Satisfaction is doing the penance given us by the priest.

The penance given by the priest does not always make full satisfaction for our sins. We should therefore add to it other good works and penances, and try to gain Indulgences.

An Indulgence is a remission, granted by the Church, of the temporal punishment which often remains due to sin after its guilt has been forgiven.