The Divine Office or the Liturgy of the Hours formed the official structure of monastic life and worship. The word “hour” in this context refers not to a 60-minute period, but to an appointed time for prayer. There are traditionally eight hours in the Office:
Matins (during the night, at about 2 a.m.); also called Vigil and perhaps composed of two or three Nocturns, i.e., groups of psalms, antiphons, and readings
Lauds or Dawn Prayer (at dawn, about 5 a.m., but earlier in summer, later in winter)
Prime or Early Morning Prayer (First Hour = approximately 6 a.m.)
Terce or Mid-Morning Prayer (Third Hour = approximately 9 a.m.)
Sext or Midday Prayer (Sixth Hour = approximately 12 noon)
None or Mid-Afternoon Prayer (Ninth Hour = approximately 3 p.m.)
Vespers or Evening Prayer (“at the lighting of the lamps,” about 6 p.m.)
Compline or Night Prayer (before retiring, about 7 p.m.)