In the Sacrament of Holy Orders, or Ordination, the priest being ordained vows to lead other Catholics by bringing them the sacraments (especially the Eucharist), by proclaiming the Gospel, and by providing other means to holiness.
As people of God, we all share in the priesthood of Christ, and so the Church speaks meaningfully of "the priesthood of all believers." Each of us is to exercise our priesthood by strengthening and serving one another. Within the Church there are many means of service. One way of service stands out as a sacrament, namely Holy Orders, which ordains the recipient to the office of bishop, priest or deacon.
The priest's special calling is first and foremost to preach the Good News of God's love and humanity. In offering himself as a candidate for the priesthood, he must give evidence of wisdom and spiritual maturity, as he is called to lead the Christian community with patience and kindness. The priest celebrates Mass and administers the Sacraments, taking an active role in offering Christ's gift of Himself.
From earliest times, deacons have had a special place in the pastoral work of the Church, preaching, ministering at baptisms and weddings, and caring for the poor and hungry on behalf of the whole Church. Nowadays, married men are more and more frequently ordained to the diaconate, where they have a strong role in assisting priests and bishops and serving the people.
Finally, bishops are chosen and ordained to supervise and lead priests and deacons, to unify, bless and teach the people and act as a sign of Christ in the local church and community.