Penance means to regret, to repent for the sins committed. It is also called confession in our church. It is one of the sacraments of the Church by which we are justified and cleansed and given absolution. Through Penance a sinful man by sincere and perceptive repentance and by earnest confession receives absolution of sins. The notion and idea of Penance comes from the Old Testament. However our Lord, Jesus Christ reinforced the idea of penance stronger and turned it into a new spiritual reality. The Lord refers to Penance many times in the Gospels: "Repent, for the kingdom of heaven has come near" Matthew 4:17; "But unless you repent, you too will all perish" Luke 13:3; “I tell you that in the same way there will be more rejoicing in heaven over one sinner who repents than over ninety-nine righteous persons who do not need to repent" Luke 15:7.
There are mainly three conditions for the sacrament of Penance. First of all the penitents should sincerely, honestly and knowingly acknowledge their sins. The second is the confession of the sins committed. Through a sincere confession one receives absolution from sins. During the apostolic times the faithful would make their confession publicly telling each other about their sins. In the Epistle of James we read his exhortation "Therefore confess your sins to each other and pray for each other so that you may be healed" (5:16).
The final condition of Penance is restoration, and this is made chiefly by prayer, fasting, and almsgiving. Just as Zaccheus confessed his sins before Jesus Christ and promised to restore fourfold anything that he had taken from any man by false accusation (Luke 19, 1-10).
It is obligatory to go to confession before Holy Communion. That is the rule of the Church. It is true that many Christians do no commit serious sins, or mortal sins, which is the technical word for heavy sins. Nevertheless, we must confess our little sins, too. If, however, somebody says I have no sins, he is lying, as the Scripture says, "If we say that we have no sin, we deceive ourselves and the truth is not in us" (I John 1: 18).
Penance, therefore, is the Sacrament through which we receive that sanctifying grace for the soul which we have lost through sin. No matter how grave our sins may have been, they are forgiven if we make a sincere contrition and a good confession. "If we confess our sins, God is faithful and just, to forgive our sins and to cleanse us from all iniquity" (I John 1: 9).
The sacrament of Penance gives the penitent, in addition, a special strength by which he will overcome temptations and lead a good life.
The works of Penance act like a medicine; not only do they cure sins but also weaken the power of evil tendencies, and give new strength to the soul.