Ordination is the rite by which a person is set apart and authorised for religious ministry or priesthood, conferring the office and, in many traditions, the spiritual authority to perform its functions. Across the religions that maintain a distinct clergy, ordination marks the boundary between the ordained minister and the general body of believers, and admits the candidate to an order, of priests, ministers, monks, rabbis or their equivalents, with its particular duties and powers. The forms and the theology of ordination vary widely, but the act commonly involves a formal setting apart before the community, often with the laying on of hands, prayer, and the bestowal of the symbols of the office.
In the Catholic, Orthodox and much of the Anglican tradition, ordination to the priesthood is regarded as a sacrament that imparts an indelible character, conferring the power to celebrate the Eucharist and absolve sins, and transmitted in an unbroken succession from the apostles through the laying on of a bishop's hands. Most Protestant churches understand ordination differently, as the church's recognition and authorisation of a person's call to the ministry of word and sacrament, rather than the conferral of a priestly power setting them ontologically apart. Beyond Christianity, the concept takes other forms: the ordination of Buddhist monks and nuns admits them to the monastic community under its rule and vows; the rabbi is authorised to teach and judge rather than to offer sacrifice; and many traditions have their own rites of investiture for their religious specialists. Ordination has also been a focus of major modern controversy, above all over the admission of women, and in some churches of openly gay clergy, to orders long reserved to men, disputes that turn on differing understandings of what ordination is and who may receive it.