linguistic:paraphrasing, information:classification
Eastern Orthodoxy

The Eastern Orthodox Church has three ranks of holy orders: bishop, priest, and deacon. These are the same offices identified in the New Testament and found in the Early Church, as testified by the writings of the Holy Fathers. Each of these ranks is ordained through the Sacred Mystery (sacrament) of the laying on of hands (called cheirotonia) by bishops. Priests and deacons are ordained by their own diocesan bishop, while bishops are consecrated through the laying on of hands of at least three other bishops.

Within each of these three ranks there are found a number of titles. Bishops may have the title of archbishop, metropolitan, and patriarch, all of which are considered honorifics. Among the Orthodox, all bishops are considered equal, though an individual may have a place of higher or lower honor, and each has his place within the order of precedence. Priests (also called presbyters) may (or may not) have the title of archpriest, protopresbyter (also called "protopriest", or "protopope"), hieromonk (a monk who has been ordained to the priesthood) archimandrite (a senior hieromonk) and hegumen (abbot). Deacons may have the title of hierodeacon (a monk who has been ordained to the deaconate), archdeacon or protodeacon.

The lower clergy are not ordained through cheirotonia (laying on of hands) but through a blessing known as cheirothesia (setting-aside). These clerical ranks are subdeacon, reader and altar server (also known as taper-bearer). Some churches have a separate service for the blessing of a cantor.

Ordination of a bishop, priest, deacon or subdeacon must be conferred during the Divine Liturgy (Eucharist)—though in some churches it is permitted to ordain up through deacon during the Liturgy of the Presanctified Gifts —and no more than a single individual can be ordained to the same rank in any one service. Numerous members of the lower clergy may be ordained at the same service, and their blessing usually takes place during the Little Hours prior to Liturgy, or may take place as a separate service. The blessing of readers and taper-bearers is usually combined into a single service. Subdeacons are ordained during the Little Hours, but the ceremonies surrounding his blessing continue through the Divine Liturgy, specifically during the Great Entrance.

Bishops are usually drawn from the ranks of the archimandrites, and are required to be celibate; however, a non-monastic priest may be ordained to the episcopate if he no longer lives with his wife (following Canon XII of the Quinisext Council of Trullo) In contemporary usage such a non-monastic priest is usually tonsured to the monastic state, and then elevated to archimandrite, at some point prior to his consecration to the episcopacy. Although not a formal or canonical prerequisite, at present bishops are often required to have earned a university degree, typically but not necessarily in theology.

Usual titles are Your Holiness for a patriarch (with Your All-Holiness reserved for the Ecumenical Patriarch of Constantinople), Your Beatitude for an archbishop/metropolitan overseeing an autocephalous Church, Your Eminence for an archbishop/metropolitan generally, Master or Your Grace for a bishop and Father for priests, deacons and monks, although there are variations between the various Orthodox Churches. For instance, in Churches associated with the Greek tradition, while the Ecumenical Patriarch is addressed as "Your All-Holiness", all other Patriarchs (and archbishops/metropolitans who oversee autocephalous Churches) are addressed as "Your Beatitude".

Orthodox priests, deacons, and subdeacons must be either married or celibate (preferably monastic) prior to ordination, but may not marry after ordination. Re marriage of clergy following divorce or widowhood is forbidden. Married clergy are considered as best-suited to staff parishes, as a priest with a family is thought better qualified to counsel his flock. It has been common practice in the Russian tradition for unmarried, non-monastic clergy to occupy academic posts.