Matins

Matins is a principal hour of the daily liturgical cycle. As celebrated in the Byzantine Rite, it combines:

         A service of prayers for rulers and those in authority (the "Royal Office", originally celebrated in monasteries under Imperial patronage);  this office is usually omitted in parish celebrations

         A nocturnal vigil consisting of psalms and Scripture readings

         A service of praise, sometimes called Lauds, and including Psalms 148-150 and the hymn, "Glory to God in the highest"

Matins has three principal themes: repentance for our sins and offences; meditation on the history of salvation; and praise of God.  On Sundays, hymns are added which focus on the Resurrection of Christ and the events that surrounded it.  On feast days, hymns for the feast are sung, and the icon of the feast may be enthroned and venerated.

Matins for Sundays and feasts may be combined with Vespers (or Compline) to form the All-Night Vigil.

Source: www.metropolitancantorinstitute.org