Catechism of the Catholic Church §2179 — excerpt
"A parish is a definite community of the Christian faithful established on a stable basis within a particular church; the pastoral care of the parish is entrusted to a pastor as its own shepherd under the authority of the diocesan bishop."
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.
Also cites: CIC, can. 515 # 1 · St. John Chrysostom, De incomprehensibili 3, 6: PG 48, 725