Great Vespers is a beautiful evening service served on Saturdays and before major feast days. The liturgical day begins at sunset, and Vespers is the first service in the daily cycle. On Saturdays, the Vespers service focuses on the Resurrection of Jesus Christ and begins at 5:00 pm.
The service consists of the reading of Psalms, the ancient hymn O Gladsome Light, hymns about Christ’s Resurrection or the feast day, the Song of Saint Simeon (Luke 2), and other prayers and hymns.
Orthros (also called Matins) is the Church’s fourth and final liturgical service of the night. It is served before Divine Liturgy on Sundays (9:00 am) and major feast days.
The service consists of the reading of the Six Psalms*, the Evlogitaria (“Blessed”), the reading of the Resurrectional Gospel, the Lauds (the Praises), the ancient hymn The Great Doxology, and other prayers and hymns.
The Divine Liturgy is the primary worship service of the Church, centered around the Holy Mystery of the Eucharist (“Communion” or “the Lord’s Supper”). In the Eucharist, the real body and blood of Jesus Christ in his eternal sacrifice, mysteriously brings us his divine life.
There are several forms for the Divine Liturgy, but that of Saint John Chrysostom has become the standard form. The Divine Liturgy of Saint Basil is used on a few special occasions throughout the year. The Divine Liturgy consists of three main parts:
Liturgy of Preparation (Prothesis)
The Prothesis is performed in private before the other services begin. The bread (prosphora) and wine for the Eucharist are prepared while the priest reads from the Prophets concerning the death of Jesus Christ.
Liturgy of the Catechumens
This portion of the Divine Liturgy focuses on worship of God the Holy Trinity in song, readings from the New Testament†, and a sermon.
In ancient times, those who were not baptized Orthodox Christians (Catechumens, “Instructed Ones”) were dismissed after the sermon. Today, however, visitors are welcome to stay (please see sidebar).
Liturgy of the Faithful
The final portion of the Liturgy concerns the “unbloody sacrifice” of the Eucharist. The ceremony is highly symbolic and represents major events from the days surrounding Christ’s death and resurrection. Following his command to “take, eat…take, drink”, the faithful are given his true body and true blood in this most holy Mystery. After giving thanks, the people depart in peace.
* The Six Psalms (Hexapsalmos) are Psalms 3, 37, 52, 87, 102, and 142 (by the Septuagint canon of scripture). While they are read at Orthros, the priest silently reads twelve prayers at the altar. There is a tradition that the time it takes to read the Six Psalms is the time it will take for Christ to judge all of humanity at the Last Judgment. —OrthodoxWiki
† The New Testament is the latter section of the Bible, consisting of 27 books. The Gospels (“Good News”) are the first four, accounts of Jesus Christ’s life and teachings. The following 22 books are the Epistles (“Letters”), consisting of 21 letters of Christ’s Apostles and The Acts of the Apostles, the account of the first few years of the Church. For various reasons, the last book of the New Testament, The Apocalypse of John (or Revelation) is not read in liturgical services.