The Sacrament of Holy Orders is a sacrament of service to the entire Body of Christ, the Church. It is a continuation of Christ’s priesthood which He gave upon his Apostles, hence it is called “apostolic ministry” in the Catechism of the Catholic Church.
By the laying on of hands of the apostles and their successors, the power of the Holy Spirit is poured out on each generation to save and to sanctify. “Ordination” comes from the Latin word ordinatio, which means to incorporate someone into an order. In the Sacrament of Holy Orders, a man is incorporated into the priesthood of Christ at one of three levels: the episcopate, the priesthood, or the diaconate.