Excerpt from Lumen Gentium, Dogmatic Constitution on The Church
Pope Paul VI

http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html

The pope's power of primacy over all, both pastors and faithful, remains whole and intact. In virtue of his office, that is as Vicar of Christ and pastor of the whole Church, the Roman Pontiff has full, supreme and universal power over the Church.
For our Lord placed Simon alone as the rock and the bearer of the keys of the Church, and made him shepherd of the whole flock; it is evident, however, that the power of binding and loosing, which was given to Peter was granted also to the college of apostles, joined with their head. This college, insofar as it is composed of many, expresses the variety and universality of the People of God, but insofar as it is assembled under one head, it expresses the unity of the flock of Christ. (#22)

The Roman Pontiff, as the successor of Peter, is the perpetual and visible principle and foundation of unity of both the bishops and of the faithful. The individual bishops, however, are the visible principle and foundation of unity in their particular churches, fashioned after the model of the universal Church, in and from which churches comes into being the one and only Catholic Church. For this reason the individual bishops represent each his own church, but all of them together and with the Pope represent the entire Church in the bond of peace, love and unity. (#23)