“Here I am, send me.”
Is 6:8
Holy Orders is the sacrament by which bishops, priests and deacons are ordained and receive the power and grace to perform their sacred duties. The sacred rite by which orders are conferred is called ordination. The apostles were ordained by Jesus at the Last Supper so that others could share in his priesthood.
There are three levels of participation in the Sacrament of Holy Orders: as bishop, as priest (from presbyter, which is Greek for “elder”), and as deacon.
A bishop receives the fullness of the Sacrament of Holy Orders. He is the head or Ordinary of the local church. The local area entrusted to him is called a diocese. A bishop is also a member of the episcopal college: this is all the bishops who, with the pope, guide the Church.
Priests serve the community in various ways. They may be called to serve in their dioceses or as religious order priests, carrying out the mission of a particular religious community. They preside at liturgies, preach, administer the sacraments, counsel people, serve as pastors, and teach.
Deacons help and serve bishops by serving the needs of the Church, proclaiming the gospel, teaching and preaching, baptizing, witnessing marriages, and assisting the priest celebrant at liturgies.