Catechism of the Catholic Church §985 — excerpt
Baptism is the first and chief sacrament of the forgiveness of sins: it unites us to Christ, who died and rose, and gives us the Holy Spirit.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.