The Act of Contrition is said after confession and after the priest has given a Catholic petitioner Penance and Absolution. Penance is a sacrament which reconciles a Catholic to God and the Church. Penance may consist of doing charity work or performing a set of prayers.
The Act of Contrition is a prayer in which the supplicant asks God to forgive his sins. It is believed the sinner must truly be sorry for the sins and resolve never to repeat them. Sins are typically confessed in the church confessional and then the sacrament of Penance is given by the priest. After Penance, the priest offers Absolution which means the sinner is forgiven. At this time, the petitioner recites the Act of Contrition alone or with the priest. It is advisable to print a copy and keep it with you when you go to into the confessional.