Also called “Penance” and “Confession”, was instituted when Jesus told his apostles, “Whose sins you forgive, they are forgiven; whose sins you do not forgive, they are not forgiven.” Reconciliation is poorly understood by many. Although the father was always willing to forgive the prodigal son, it could not happen until the son returned to the father. Reconciliation is the way we return to the Father who wants to forgive us. The priest receives the power of Jesus to forgive sin at his ordination; he also stands in for the community, since all sin offends our neighbor as well as God. We mention those serious offenses and any other issues (eg, bad habits) which interfere with our relationship with God. After we make an act of contrition (the intention not to commit those sins again) The priest absolves us in the name of the Holy Trinity. A penance, usually a prayer or two, is assigned.
The sacrament of reconciliation can be arranged with a priest, and parishes also have times published in their bulletins when the sacrament is available without an appointment. You can receive the sacrament anonymously, or face to face with the priest. If the priest gets to know you, he can often help with spiritual direction as well as forgiving your sins. Catholics are supposed to receive the sacrament of reconciliation at least annually if they are aware of serious sin; many people receive it as often as once a week.
Whether one has committed a serious (mortal) sin is a judgment that only the sinner can make. The sin must be objectively evil; the sinner must know that it is evil; and the sinner must willingly and without coercion choose to commit it. Acts which are objectively evil include murder and abortion, theft, slander, lying, etc. Since the sinner freely chooses to disobey God, his relationship with God is severed until reconciliation takes place.
In addition to the forgiveness of sins, the sacrament confers God's grace to help us avoid sin and grow in holiness.