A psalter is a volume containing the Book of Psalms, often with other devotional material bound in as well, such as a liturgical calendar and litany of the Saints.
Dedicated psalters, as distinct from copies of the Psalms in other formats, e.g. as part of a full edition of the Old Testament, were first developed in the Latin West in the 6th century in Ireland and from about 700 on the continent.
The extensively illustrated Utrecht Psalter is one of the most important surviving Carolingian manuscripts and exercised a major influence on the later development of Anglo-Saxon art.
From the late 11th century onwards they became particularly widespread - Psalms were recited by the clergy at various points in the liturgy, so psalters were a key part of the liturgical equipment in major churches.
Historiated initials or full-page illuminations were used to mark the beginnings of the major divisions of the Psalms, or the various daily readings, and may have helped users navigate to the relevant part of the text, as medieval books almost never had page numbers.
[3] Scholar John Gee has argued that this represents a cultural continuation of the ancient Egyptian tradition of placing the Book of the Dead in tombs and sarcophagi.
[4] The Pahlavi Psalter is a fragment of a Middle Persian translation of a Syriac version of the Book of Psalms, dated to the 6th or 7th century.
In Orthodox Christianity, the Book of Psalms for liturgical purposes is divided into 20 kathismata or "sittings", for reading at Vespers and Matins.