One of the most beloved portions in all the Scriptures is the book of Psalms. Some of the most loved, most recited, and most treasured passages of Scripture are found there. Nearly everyone is familiar with at least a portion of Psalm 23. A life of reflecting upon the contents of the Psalms would beget countless profit in the Christian’s life. The Hebrew title is the Book of Praises. The word psalm coming from Greek translation (via the Latin Vulgate) of the Hebrew term mizmôr, a song accompanied with a string instrument which came to mean “praises.” Whether this accurately reflects the meaning of the term, it does accurately reflect the meaning of the book as each Psalm (except Ps 88, which actually uses this case to great rhetorical affect) ends in praise.
The Psalms do not have a single author. In fact, there is scholarly debate about the meaning of the superscriptions which attribute authorship of some Psalms to David, Solomon, the Sons of Korah, or others. The grammar is likely not exclusive in referring to authorship. But the construction “of” plus a name (e.g. of David) likely refers to authorship. While this topic is debated, it is not debated that the book of Psalms is a collection of a number of writers. Psalm 90 is attributed to Moses, and likely written around 1400BC. Psalms 3-42 and 51-70 are “of David.” Psalms 42-49 are “of the Sons of Korah.” Other psalms were written as late as the postexilic time (c. 400BC), such as Psalm 137 which begins, “By the water of Babylon, there we sat and wept, when we remembered Zion.” This means the books of Psalms was composed by a variety of authors over the course of a 1000 years, all of it superintended and guided by the Holy Spirit.
There are three main types of Psalms (Hymns, Laments, and Thanksgivings). This division gives the Psalms a diversity that allows it to cover the whole of human experience. John Calvin says in the introduction to his commentary on the Psalms:
I have been accustomed to call this book, I think not inappropriately, ‘An Anatomy of all the Parts of the Soul;’ for there is not an emotion of which any one can be conscious that is not here represented as in a mirror. Or rather, the Holy Spirit has here drawn to the life all the griefs, sorrows, fears, doubts, hopes, cares, perplexities, in short, all the distracting emotions with which the minds of men are wont to be agitated.
For every circumstance of life, there is a Psalm that speaks God’s voice into the reality of your situation.
The Psalms are not, however, just a jumbled collection or anthology of poetry. There is a clear and intentional structure to it. The laments of the Psalms tend to be at the front end. Thus, there is a movement from lamentation to praise and from suffering to glory. There is a Christological bent to this movement, as reflected in Jesus’ instruction to the two on the Road to Emmaus, “Was it not necessary that the Christ should suffer these things and enter into his glory?” (Lk 24:26). In addition to this emotive structure, there is also a division of the Psalms into five books. Book 1 (1-42), book 2 (42-72), book 3 (73-89), book 4 (90-106), and book 5 (107-150). Books 1-4 are marked by doxologies to close out the book. Book 5 ends with 5 Psalms (146-150) which serve as a grand doxology to the whole collection. It is also generally accepted that Psalms 1-2 serve as a formal introduction to the whole of the Psalms. As such, they give important clues to the overall meaning of the Psalms.
The Psalms are teachings on the blessed life. Like the 5 books of Moses teach (torah) and instruct about the Lord, the 5 books of the Psalms teach about the blessed life. John Calvin argues in the introduction of his commentary that no other place so perfectly teaches how to worship God, to seek happiness in him, and to find remission of sin through Christ. Psalm 1 focuses in on this aspect of the whole book of Psalms. But Psalm 2 then explains that the blessed life of Psalm 1 is found in the blessed reign of the Lord as King. The Psalms explain that God is King and he is coming to transform suffering into glory and to provide for his subjects the blessed and abundant life. From the depths of suffering to the heights of glory, the Psalms teach us the blessed life found in the good reign of Christ as our King.
 Waltke and Yu, An Old Testament Theology, 871.
 John Calvin and James Anderson, Commentary on the Book of Psalms, xxxvi–xxxvii.
 Van Pelt et al., A Biblical-Theological Introduction to the Old Testament, 345.
 John Calvin and James Anderson, Commentary on the Book of Psalms, xxxviii–xxxix.