The Psalms are beautiful poetic songs of prayer. The Psalms convey three important themes of Hebrew Scripture - that God is active in history, the necessity of human response to God through praise and prayer, and the beginning of wisdom is fear of the Lord and to Trust in God. The Psalms of Hebrew Scripture are composed of songs of praise sung to God in divine worship, accompanied by a musical instrument. The word Psalm in Hebrew - תְּﬣִﬥָﬣ - tehillah - aactually means praise or song of praise. King David sang a song of praise to the Lord when he was delivered from the grasp of his enemies and from the hands of Saul (Second Samuel 22:1). Their time of composition was primarily pre-exilic (before 586 BC, the time of the Babylonian exile) and post-exilic (after 516 BC), but the time probably ranges over five centuries. The authorship of 73 of the Psalms is attributed to David, although it is likely that he composed one or more of the 48 anonymous Psalms. Psalm 89 is attributed to Moses and Psalms 71 and 126 to Solomon.

The Psalms begin the Writings or Hagiographa in the three-fold division of the Law of Moses, the Prophets, and Writings of Hebrew Scripture. In the four-fold division of the Greek Septuagint, the Latin Vulgate, and the Christian Old Testament of the Bible, the Psalms are part of the Wisdom Literature, which includes in the following order: the Books of Job, Psalms, Proverbs, Ecclesiastes, and the Song of Songs. The Greek Septuagint and Latin Vulgate also included the Books of Wisdom and Sirach.

The Hebrew Psalms number 150, while the Dead Sea Scrolls as well as the Greek Septuagint Old Testament both contain Psalm 151 of David. The numbering of Psalms often differ by one, the Hebrew Psalter being one more than the Greek Septuagint and Latin Vulgate. The numbering here follows the original Greek Septuagint. The Psalms are generally of three types: laments, both individual and communal; hymns; and songs of thanksgiving. Others are classified as royal psalms, some wisdom psalms, and others defy classification.

At one time, the Psalms were divided into five books to correspond to the Pentateuch of Moses. Book I includes Psalms 1-39, attributed to David. Book II comprises Psalms 41-71, authored by the Sons of Korah, Asaph, David, and Solomon. Book III has Psalms 72-88, composed primarily by Asaph and the Sons of Korah, with Psalm 85 by David and Psalm 89 by Ethan. Book IV contains Psalms 89-105 without named authors except for Psalm 89 (Moses) and Psalms 100 and 102 (David). Book V covers Psalms 106-149, which include Psalm 109 by David; Psalms 112-117, the Hallel sung during Passover; Psalms 119-133, the Songs of Ascents; and 137-144 composed by David. Unifying themes include contemplation and prayer to the Lord and Love.

Placing our trust in God is found throughout the Scriptures, especially the Psalms. The Hebrew verb to trust -
בָּטַח - baṭaḥ - or its conjugates are recoorded over 40 times in the Psalms alone, and to Trust in God is the primary theme of such Psalms as 3, 26, 55, and 61. Trusting in God means both to believe in God and to place our hope in Him. Thus in Greek one sees the word trust translated both with the verbs for faith - πιστεύω - I believe, have faith in, trust; and hope - ἐλπίζω - I hope, trust. Another Greek verb that conveys the meaning of trust is πέποιθα - I depend on, trust.

The Psalms have had a profound influence on both Eastern and Western culture. The most famous Psalm is King David's Psalm 22. Christ repeats verse six of Psalm 30 on the Cross, "Into thy hands I commend my spirit." Psalm 90 offers evidence of Guardian Angels.  Angels carry out the will of God.  Psalm 117 (verse 24) was the inspiration for the World War I liberation song of Jerusalem, the world-famous Hava Nagila. Psalm 118 is an alphabetical psalm that expresses love for the Word of God, each eight-verse stanza beginning with one of the 22 letters of the Hebrew alphabet. Psalm 138 speaks of life in the womb!

The Psalms are notable for Prophecies of the Messiah, such as Psalm 2, fulfilled in Matthew 3:17, Psalm 21, fulfilled in the crucifixion of Jesus Christ, and Psalm 109. In fact, the greatest number of Old Testament quotations found in the New Testament are from the Book of Psalms, Psalm 109 being the most quoted by New Testament writers. For example, God declared his son Jesus Christ high priest according to the order of Melchizedek in Hebrews 5:10, which fulfilled Psalm 109, a Psalm of David, in which David announced to his royal successor - "You are a priest forever after the order of Melchizedek" (Psalm 109:4). Melchizedek, whose name is found only twice in Hebrew Scripture, was the king of Salem and a priest of God Most High, who brought out bread and wine and blessed Abram (Genesis 14:18). Psalm 75:2 locates Salem of Genesis 14:18 to Jerusalem.

Following the destruction of the Jerusalem Temple in 587 BC, when animal sacrifice could no longer be continued, a sacrifice of praise was instituted among the Jewish people during the Babylonian Exile, which included readings of the Torah, Psalms, and Hymns throughout the day. The risen Christ applied the Psalms to himself when he said to his disciples: "Everything written about me in the Law of Moses, the Prophets, and the Psalms must be fulfilled" (Luke 24:44). This sacrifice of praise continued within Christianity as the Lectio Divina, which is extensive Scripture readings from both the New Testament and Old Testament, the Gradual Psalm and the Seven Penitential Psalms from the Septuagint Text.  The Penitential Psalms from the Septuagint text are 6, 31, 37, 50, 101, 129, 142. The daily Mass and the reading and praying of Scripture are the heart of the Rule of St. Benedict.