Catechism of the Catholic Church §1623 — excerpt
In the Latin Church, it is ordinarily understood that the spouses, as ministers of Christ's grace, mutually confer upon each other the sacrament of Matrimony by expressing their consent before the Church.
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.