All the baptised share in the common priesthood of Christ in that we all share in his mission of spreading the Good News and building the kingdom here on earth.
To assist this common priesthood of the faithful there is another form of priesthood which is conferred by the Sacrament of Holy Orders. Ordination confers a sacred power for the service of the faithful by which the ordained teach the faithful, lead divine worship, and oversee the running of the Church.
There are three degrees in the ordained priesthood – bishop, priest and deacon.
At the head of the Church is the bishop who also represents Christ as the shepherd of the flock.
Working with him are his priests who receive their authority to minister from him.
Assisting these are the deacons who are servants of the Church. In the Roman and Orthodox Churches, only men may be ordained for ministerial service and only a bishop may ordain. (Catechism 1536-1600)