Matins

Matins is the monastic nighttime liturgy, ending at dawn, of the canonical hours. As standardized in the Roman Catholic Liturgy of the Hours, it is divided into three Nocturns. The name "Matins" originally referred to the morning office also known as Lauds. When the nocturnal monastic services called Vigils or Nocturns were joined with Lauds, the name of "Matins" was applied at first to the concluding morning service and later still to the entire series of Vigils.

In Eastern Orthodoxy these Vigils correspond to the All-night Vigil comprising the Midnight Office and the daybreak service of Orthros (in Church Slavonic: Oútrenya).

Mattins, usually but not always spelt with a double "t", is the Anglican Morning Prayer which consolidated the hours of Matins, Lauds and Prime. Lutherans preserve recognizably traditional Matins distinct from Morning Prayer, but "Matins" is sometimes used in other Protestant denominations to describe any morning service.

Read more about Matins:  Eastern Christianity, Non-Roman Western Rites