About the Sacrament
The whole Church is a priestly people. Through Baptism all the faithful share in the priesthood of Christ. This participation is called the “common priesthood of the faithful.” Based on this common priesthood and ordered to its service, there exists another participation in the mission of Christ: The ministry conferred by the sacrament of Holy Orders, where the task is to serve in the name and in the person of Christ the Head in the midst of the community.
The ministerial priesthood differs in essence from the common priesthood of the faithful because it confers a sacred power for the service of the faithful. The ordained ministers exercise their service for the People of God by teaching (Munus docendi), divine worship (munus liturgicum) and pastoral governance (munus regendi).
Since the beginning, the ordained ministry has been conferred and exercised in three degrees: that of bishops, that of presbyters, and that of deacons.
The bishop receives the fullness of the sacrament of Holy Orders, which integrates him into the Episcopal college and makes him the visible head of the particular Church entrusted to him. As successors of the apostles and members of the college, the bishops share in the apostolic responsibility and mission of the whole Church under the authority of the Pope, successor of St. Peter.
Priests are united with the bishops in sacerdotal dignity and at the same time depend on them in the exercise of their pastoral functions; they are called to be the bishops’ prudent co-workers. They form around their bishop the presbyterium, which bears responsibility with him for the particular Church. They receive from the bishop the charge of a parish community or a determinate ecclesial office.
Deacons are ministers ordained for tasks of service of the Church; they do not receive the ministerial priesthood, but ordination confers on them important functions in the ministry of the word, divine worship, pastoral governance, and the service of charity, tasks which they must carry out under the pastoral authority of their bishop. (Catholic Catechism)