The Psalms are the divinely-inspired songs of the People of Israel. They are traditionally called the "psalms of David," although many of them most certainly come from other authors of much later times. The enumeration and the wording of the psalms differ in various scriptural traditions. The Orthodox Church follows the Septuagint version of the psalter and for this reason the numbers and not seldom the texts of certain psalms are different in Orthodox service books from what they are in the Bibles which are translated from the Hebrew.
In the Orthodox Church, the entire psalter is divided into twenty sections and is chanted each week in those monasteries and churches which perform the entire liturgical office. Various psalms and verses of psalms are used in all liturgical services of the Orthodox Church.
Virtually all states of man's soul before God are found expressed in the psalms: praising, thanking, blessing, rejoicing, petitioning, repenting, lamenting, questioning and even complaining. Many of the psalms are centered in the cultic rituals of the Jerusalem temple and the Davidic kingship. Others recount God's saving actions in Israelite history. Still others carry prophetic utterances about events yet to come, particularly those of the messianic age. Thus, for example, we find Christ quoting Psalm 8 in reference to His triumphal entry into Jerusalem; Psalm  110 in reference to his own mysterious divinity; and Psalm  22, when, hanging upon the cross, He cries out with the words of the psalm in which is described His crucifixion and his ultimate salvation of the world (See Mt 21:16, 22:44, 27:46).
In the Orthodox Church all of the psalms are understood as having their deepest and most genuine spiritual meaning in terms of Christ and His mission of eternal salvation. Thus, for example, the psalms which refer to the king are sung in the Church in reference to Christ's exaltation and glorification at the right hand of God. The psalms which refer to Israel's deliverance are sung in reference to Christ's redemption of the whole world. The psalms calling for victory over the enemies in battle refer to the only real Enemy, the devil, and all of his wicked works which Christ has come to destroy. Babylon thus signifies the realm of Satan, and Jerusalem, the eternal Kingdom of God. The psalms which lament the innocent suffering of the righteous are sung as the plea of the Lord Himself and all those with Him who are the "poor and needy" who will rise up to rule the earth on the day of God's terrible judgment. Thus, the psalter remains forever as the divinely-inspired song book of prayer and worship for all of God's People, and most especially for those who belong to the Messiah whose words the psalms are in their deepest and most divine significance.