In the Catholic Church, monasteries and convents recognize particular times of day for prayer. These prayer times traditionally occur seven times a day. Vespers and Compline close the canonical hours at evening.
Bishop Thomas Cranmer authored the divorce plea from Catherine of Aragon for Britain's King Henry VIII. When the Pope rejected the request, Henry made his world-changing break with the Catholic Church. Cranmer followed his king, and subsequently put together the Anglican liturgy in the Book of Common Prayer. Knowing it would not be politic to appear "too Catholic," but recognizing people were accustomed to praying at the canonical hours, Cranmer combined the evening prayers of Vespers and Compline into one act of worship: Evensong.
Evensong, "evening song," is said or sung daily at most cathedrals. Essentially, it thanks God for the day just past and asks his protection during the coming night. It is a quiet, reflective set of prayers, songs and psalms, asking the worshiper to be still in spirit.
The form for evensong can vary, but it usually follows the Book of Common Prayer in the responses, Psalms and antiphons offered. The service generally opens with a responsorial praise of God: the preces. Then the Magnificat (Mary's song from Luke 1: 46-55) is often sung, followed by Nunc Dimittis (Simeon's Song from Luke 2: 28-30)and a Psalm, such as Psalm 67. A hymn is sung and a responsorial prayer is said. The worshipers are then sent forth to serve.
Scripture readings from the day's lectionary are also included in the evensong service, along with the Apostle's Creed. Liturgy may be subtracted or added, depending on which form of the service is being used that day in that church. The Book of Common Prayer and the Common Worship Book each have a different form of Evensong, but both are beautiful and meaningful to worshipers.
The Christian church as a whole has always felt it helpful to pray both morning and evening, and an Evensong service helps Christians close their days with quiet reflection and thankfulness to God.