The Church Canon requires 9 various services (offices) to be performed during the day. Each of them has its history, symbolism and duration, but spiritually they form one whole thing called the daily circle.
The Orthodox service borrowed many things from Old Testimony prayer traditions. For instance, a new day is considered to begin not at midnight, but at 6 p.m. Thus the first office of the daily circle is the Vespers. During Vespers the faithful are reminded of the main events of the Holy History of the Old Testament: the creation of the universe by God, the sin of Adam and Eve, the Law of Moses and the work of the Prophets. Christians thank God for the day just passed.
After the Vespers we are to serve Compline. This is something like common prayers for the coming night, which reminds us of Christ’s descending to hell and freeing the righteous people from the power of the devil.
At midnight the third service of the daily circle is read, which is called Nocturnes (Midnight office). This service is to remind the faithful about the second coming of the Lord and the Last Judgment.
Matins begins before sunrise. It is devoted to the events of Christ’s earthly life and consists of many prayers of repentance and thanksgiving. Matins is one of the longest services.
Around 7 o’clock a.m. we are to serve the First hour. This is the name of the short service during which the Church remembers Jesus Christ being judged by the high priest Caiaphas.
The Third hour (10 a.m). takes us through holy recollections to the mount of Zion where the Holy Spirit descended upon the Apostles, and to the praetor’s quarters of Pilate, where the Christ was sentenced to death.
The Sixth hour (noon) is the time of Christ’s crucifixion, and the Ninth hour (3 p.m). is the time of His death on the Cross. These offices are devoted to those tragic events respectively.
And finally, the main Christian service, a certain center of the circle of offices is the Divine Liturgy. This office not only reminds us of God, but also makes it possible actually to join Him in the mystery of Holy Communion. This office is to be served between the Sixth and the Ninth hour.
Contemporary worshiping practice has introduced some changes into the rules of The Church Canon. Thus, in parishes Compline is served only during the Great Lent, and the Nocturnes — only once a year, on the eve of Easter. The Ninth hour is served very rarely too. The rest of the six offices are combined into two groups, each consisting of three services.
In the evening Vespers, Matins and the First hour are served. On the eve of Sundays and Holidays this sequence of offices is called the All night vigil, which means staying awake all through the night. Ancient Christians were indeed praying till sunrise. Contemporary vigils last generally about 2-4 hours in parishes and 3-6 hours in monasteries.
In the morning the Third hour, the Sixth hour and the Divine Liturgy are served consecutively.
On the days when Liturgies cannot be served (as on Friday of the Passion Week), a short office of Typika is served. This service includes some Liturgical chants and can be said to portray the latter. But Typika does not have the status of a complete service.