Catechism of the Catholic Church §805 — excerpt
The Church is the Body of Christ. Through the Spirit and his action in the sacraments, above all the Eucharist, Christ, who once was dead and is now risen, establishes the community of believers as his own Body.
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.