This is a prayer which is used not only in daily devotions but on many other occasions - in the Sacrament of Penance, in the Divine Office, and especially... at the beginning of the Mass.

Like the Creed, it takes its name from its first word. "Confiteor," in Latin, means "I confess." The Confiteor is a general confession of sin, an acknowledgment of guilt, made in the presence of God and His Saints, and a prayer that the Saints may intercede for the sinner.

The Confiteor was originally a part of the private prayers offered by the priest in preparation for Mass, expressing his unworthiness and asking for grace and forgiveness. After a time, about the tenth century, it became customary for the priest to say this prayer at the foot of the altar [before the reforms of Vatican II], and gradually it came to be regarded as a part of the Mass....

Until quite recently it was usual to recite the first part of the Confiteor in the confessional before making the accusation of sins; but at the present time, for the sake of expediting the confession, it is recommended that it be said before entering, and that only the words "I confess to Almighty God and to you, Father, [that I have sinned]" be used in the confessional.

Asking the Intercession of Saints. Why do we say the Confiteor? Why should one confess his sins to the Blessed Virgin and to the Saints, none of whom have any power to absolve from sin? This objection may be found in some Protestant works. We answer that it is reasonable to make a general acknowledgment of our weakness and guilt before these as well as before God, because we wish their prayers in order to secure His pardon...

May almighty God have mercy on us,

forgive us our sins,

and bring us to everlasting life.

Amen.