Catechism of the Catholic Church §938 — excerpt
The Bishops, established by the Holy Spirit, succeed the apostles. They are "the visible source and foundation of unity in their own particular Churches" (LG 23).
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.