The Confiteor (so called from the first word, confiteor, I confess) is a general confession of sins; it is used in the Roman Rite at the beginning of Mass and on various other occasions as a preparation for the reception of some grace. (The Catholic Encyclopedia, Volume IV, 1908 edition)
CONFITEOR Deo omnipotenti, beatae Mariae semper Virgini, beato Michaeli Archangelo, beato Ioanni Baptistae, sanctis Apostolis Petro et Paulo, et omnibus Sanctis, quia peccavi nimis cogitatione, verbo et opere: mea culpa, mea culpa, mea maxima culpa. Ideo precor beatam Mariam semper Virginem, beatum Michaelem Archangelum, beatum Ioannem Baptistam, sanctos Apostolos Petrum et Paulum, et omnes Sanctos, orare pro me ad Dominum Deum nostrum. Amen
I CONFESS to almighty God, to blessed Mary ever Virgin, to blessed Michael the Archangel, to blessed John the Baptist, to the holy apostles Peter and Paul, and to all the saints that I have sinned exceedingly in thought, word, and deed, through my fault, through my fault, through my most grievous fault. Therefore, I beseech blessed Mary ever Virgin, blessed Michael the Archangel, blessed John the Baptist, the holy apostles Peter and Paul, and all the saints, to pray for me to the Lord our God. Amen.