Canonical hours

In the practice of Christianity, canonical hours mark the divisions of the day in terms of fixed times of prayer at regular intervals. A book of hours, chiefly a breviary, normally contains a version of, or selection from, such prayers.^[1][2]

In the Roman Rite of the Catholic Church, canonical hours are also called officium, since it refers to the official prayer of the Church, which is known variously as the officium divinum ("divine service" or "divine duty"), and the opus Dei ("work of God"). The current official version of the hours in the Roman Rite is called the Liturgy of the Hours (Latin: liturgia horarum) or divine office.

In Lutheranism and Anglicanism, they are often known as the daily office or divine office, to distinguish them from the other "offices" of the Church (e.g. the administration of the sacraments).^[3]

In the Eastern Orthodox and Byzantine Catholic Churches, the canonical hours may be referred to as the divine services, and the book of hours is called the horologion (Greek: Ὡρολόγιον). Despite numerous small differences in practice according to local custom, the overall order is the same among Byzantine Rite monasteries, although parish and cathedral customs vary rather more so by locale.

The usage in Oriental Orthodox Churches, the Assyrian Church of the East, and their Eastern Catholic and Eastern Lutheran counterparts vary based on the rite, for example the East Syriac Rite or the Byzantine Rite.