IN BRIEF
The redemption won by Christ consists in this, that he came "to give his life as a ransom for many" (Mt 20:28), that is, he "loved [his own] to the end" (Jn 13:1), so that they might be "ransomed from the futile ways inherited from [their] fathers" (I Pt 1:18).
Source: Catechism of the Catholic Church (Vatican.va)