The book of Psalms is, without a doubt, the best known and most read of all the collected writings that comprise the Holy Scriptures. However, their hermeneutical interpretation is not exactly easy and their reading inevitably raises many questions: Who were the 'enemies' referred to in the Psalms of imprecation by individual supplicants? How many actual psalms are there and what was the role of the King in worship? Why are some psalms considered sapiential? What was the Autumn Festival and what was its purpose? How do the psalms compare with similar texts of the same era? The variety of compositions, which reflect a variety of situations and emotional states, include: supplication, individual or collective; praise and thanksgiving, individual or collective; psalms of confidence; liturgical psalms; actual psalms; wisdom psalms; historical psalms, those pilgrimage; require, for correct interpretation, a deep knowledge of the composition of the Psalter, their origin and order, authors, dating, context and purpose.