The morning service of the Church is called Orthros or Matins. It opens with the reading of six morning psalms and the intoning of the Great Litany. After this, verses of Psalm 118 are sung: God is the Lord and has revealed himself to us. Blessed is he who comes In the name of the Lord. The Troparian is then sung and, if it be a monastery, various groups of psalms which differ each day are read. Once again there are hymns on the theme of the particular day. On major feast days, special praises and psalms are sung, such as on the Lord's Day when we sing of Christ's Resurrection. On major feasts and on Sundays, the Gospel is also read.
After the Gospel there is a long intercessory prayer followed by a set of hymns and readings called the Cannon. These songs are based on the Old Testament Canticles and conclude with the song of Mary, the so-called Magnificat. (Luke 1: 46-55) The Great Doxology is chanted followed by the morning litanies. The Troparian is also repeated once again before the Divine Liturgy begins.
The Orthros service of the Church unites the elements of morning psalmody and prayer with meditation on the Biblical canticles, the Gospel reading, and the particular theme of the day in the given verses and hymns. The themes of God's revelation and light are also always central to the morning service of the Church. Sometimes, particularly in churches of the Russian tradition, the Orthros and the Vesper services are combined to form a long vigil service.
Excerpt from Father Thomas Hopko, Worship: An Elementary Handbook on the Orthodox Church, v. 2, The Department of Religious Education, The Orthodox Church in America, New York, 1976, p. 66.