In the Sacrament of Penance, there are three parts, that without all these parts, this sacrament is not a sacraments. Sins are the matter, the form is "I Absolve You", said by the priest. Those words tell what is happening to the sins, the matter. But three other parts are necessary, which are also called the matter of the sacrament.
Along with the sins, we are required to have contrition, confession and satisfaction. Contrition is not only a hating of our sin, but all sin. Contrition is also not just the emotion of sorrow. Contrition is something that we choose or will, it's not just a feeling.