Canonical Hours are the seven (sometimes counted as eight) times of the day that the Catholic Church prescribes that divine office will be sung. The origins of this practice are vaguely supported by the Bible, in Psalms and Acts, but mainly sprang from medieval monastic traditions.

Each hour has a name, and is sung at or near a particular time: Matins, 3AM. Lauds, 5AM. Prime, 6AM (sunrise). Terce, 9AM (usually followed/accompanied by Mass). Sext, 12PM. Nones, 3PM. Vespers, 6PM. Compline, 8PM. Matins and Lauds are usually grouped together into one hour, and Compline is often sung later, at 9PM.

W.H. Auden wrote a great long poem "Horae Canonicae," loosely modeled after the Canonical Hours.