The book of Psalms is a book of the Hebrew Bible, also known as the Tanakh or Old Testament. It is composed of 150 psalms, which are religious songs and poems that express joy, sorrow, and other emotions. The psalms were written by various authors, including King David, and are used in Jewish and Christian worship services. They are divided into five books, each with its own theme. The book of Psalms is one of the most widely read books of the Bible and is often referred to as the 'Psalter'.