A bishop is an ordained member of the clergy who is entrusted with a position of authority and oversight in a religious institution. In Christianity, bishops are normally responsible for the governance and administration of dioceses. The role or office of the bishop is called episcopacy. Organizationally, several Christian denominations utilize ecclesiastical structures that call for the position of bishops, while other denominations have dispensed with this office, seeing it as a symbol of power. Bishops have also exercised political authority within their dioceses.
A 6th-century image of Saint Augustine, bishop of Hippo Regius
Ignatius, bishop of Antioch, student of John the Apostle
A bishop with other officials on an 11th-century grave in Sweden
Johann Otto von Gemmingen, Prince-Bishop of Augsburg
Ordination is the process by which individuals are consecrated, that is, set apart and elevated from the laity class to the clergy, who are thus then authorized to perform various religious rites and ceremonies. The process and ceremonies of ordination vary by religion and denomination. One who is in preparation for, or who is undergoing the process of ordination is sometimes called an ordinand. The liturgy used at an ordination is commonly found in a book known as an Ordinal which provides the ordo for celebrations.
Ordination of a Catholic deacon, 1520 AD: the bishop bestows vestments.
Ordination of a Catholic priest (pre-1968 form of the Roman Rite).
Ordination of an Orthodox. The deacon being ordained is kneeling with the bishop's omophorion over his head as the bishop blesses him immediately before the Cheirotonia.
Eastern Orthodox subdeacon being ordained to the diaconate. The bishop has placed his omophorion and right hand on the candidate's head and is reading the Prayer of Cheirotonia.