The Catholic hierarchy is divided into three basic categories of ordained Catholic clergy: bishops, priests and deacons. The term hierarchy comes from the Greek ἱεραρχία, meaning holy rule.

The ministry of acolyte, or altar server, was once an ordained ministry and received minor orders. Acolythus comes from the Greek ᾰ̓́κόλουθος, meaning attendant.

The title deacon comes from the Greek διάκονος, meaning servant, messenger, minister.

Priests receive Holy Orders which gives them the power to offer sacrifice and prayers to God on behalf of believers for the living and the dead, as well as to administer the sacraments of Baptism, Penance, Matrimony and Extreme Unction.

The English word bishop comes from the Greek ἐπίσκοπος, meaning supervisor. Bishops receive the fullness of Holy Orders and are considered the successors of the Apostles. The Pope is the Bishop of Rome.

Cardinals are the most prominent bishops and considered to be princes in the College of Cardinals. The name is derived from the Latin noun cardo, meaning hinge, or that upon which something depends.

The English word “pope” comes from the Greek word πάππας, meaning papa, or daddy, a term of endearment indicating spiritual fathership, in use since the earliest centuries of the Church. One of the official titles of the Pope is pontifex maximus, a term from ancient Roman times, meaning the supreme high priest.