Holy Orders is the sacrament through which the mission entrusted
by Christ to his apostles continues to be exercised in the Church
until the end of time: thus it is the sacrament of apostolic ministry.
It includes three degrees: episcopate, presbyterate, and diaconate.
(CCC 1536)
Ministerial priesthood consists of three orders:
• the order of the episcoporum - Bishop
• the order of the presbyterorum - Priest
• the order of the diaconorum - Deacon
Admission into one of these three orders is not just a matter of
election, delegation, designation, or institution, but rather as a
gift of the Holy Spirit, which comes from Christ through His Church.
(Source: The
Essential Catholic Handbook of the Sacraments)