The most significant liturgical acts reserved to priests are the administration of the seven Sacraments (known as the "Sacred Mysteries" by Eastern Christians), including the celebration of the Divine Liturgy and the Eucharist. The sacraments of Confession, Anointing of the Sick (Unction) and Chrismation are also administered by priests. In the East, Chrismation is performed by the priest immediately after Baptism, and Unction is normally performed by several priests (ideally seven), but may be done by one if necessary.
In the East, the sacraments Holy Baptism and Marriage (which is called "Crowning") may be performed only by a priest. If a person is baptized in extremis (i.e., when in fear of immediate death), only the actual threefold immersion together with the scriptural words may be done by a layperson or deacon. The remainder of the rite, and Chrismation, must still be done by a Priest, if the person survives. The only sacrament which may be celebrated only by a bishop is that of Ordination (cheirotonia, "Laying-on of Hands"), or Holy Orders.
Only men who meet certain requirements may become priests. In Orthodoxy, the normal minimum age is thirty (Can. 9 of Neocaesarea) but a bishop may dispense with this if needed. A married man may become a priest in Eastern Orthodoxy but cannot marry after ordination, even if he becomes widowed. It is also important to note that candidates for the episcopacy are only chosen from among the celibate.