The Sacrament of Holy Orders is the continuation of Christ’s priesthood, which He bestowed upon His Apostles; thus, the Catechism of the Catholic Church refers to the Sacrament of Holy Orders as “the sacrament of apostolic ministry.”
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.