Psalms gathers 150 poems that scholars classify by type more than by author: hymns of praise celebrating creation and God's kingship, laments crying out from sickness, betrayal or national defeat, songs of thanksgiving for deliverance already granted, royal psalms tied to the Davidic kingship, and wisdom psalms reflecting on the righteous and wicked life's different outcomes. The book's honesty about suffering and doubt has made it uniquely durable devotionally: Psalm 22 opens "my God, my God, why have you forsaken me," words later placed on the lips of the crucified Jesus in the Gospels, while so-called imprecatory psalms ask God directly to strike down enemies, material later readers across traditions have wrestled with rather than smoothed over.
The collection is itself organized into five books, each closing with a doxology, a structure many scholars believe deliberately echoes the five books of the Torah. Individual psalms carry an enormous range of later use: Psalm 23, "the Lord is my shepherd," is likely the single most recited passage in the entire Hebrew Bible across both Jewish and Christian funeral and comfort liturgy, while Psalm 137, mourning exile "by the rivers of Babylon," gave later music, from reggae to concert hall settings, one of its most borrowed biblical texts.