The Sacrament of Penance is the first of two sacraments of healing. The Catechism of the Catholic Church mentions in the following order and capitalization different names of the sacrament, calling it the sacrament of conversion, Penance, confession, forgiveness and Reconciliation. It is the sacrament of spiritual healing of a baptized person from the distancing from God resulting from sins committed. When people sin after baptism, they cannot have baptism as a remedy; Baptism, which is a spiritual regeneration, cannot be given a second time.
The sacrament involves four elements: (1) Contrition (the penitent’s sincere remorse for wrongdoing or sin, repentance, without which the rite has no effect); (2) Confession to a priest who has the faculty to hear confessions (Canon 966.1) – while it may be spiritually helpful to confess to another, only a priest has the power to administer the sacrament; (3) Absolution by the priest; and, (4) Satisfaction or penance.
“Many sins wrong our neighbour. 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 neighbour. 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'”. In early Christian centuries, this element of satisfaction was quite onerous and generally preceded absolution, but now it usually involves a simple task for the penitent to perform later, in order to make some reparation and as a medicinal means of strengthening against further temptation.
The priest is bound by the “seal of confession”, which is inviolable. “Accordingly, it is absolutely wrong for a confessor in any way to betray the penitent, for any reason whatsoever, whether by word or in any other fashion.” A confessor who directly violates the sacramental seal incurs an automatic excommunication whose lifting is reserved to the Holy See.
In some dioceses, certain sins are “reserved” which means only certain confessors can absolve them. Some sins, such as violation of the sacramental seal, consecration of bishops without authorization by the Holy See, direct physical attacks on the Pope, and intentional desecration of the Eucharist are reserved to the Holy See. A special case-by-case faculty from the Sacred Penitentiary is normally required to absolve these sins.