Evensong is an office1 of the Anglican church. It is supposed to be sung every evening as thanks to God for the day and a prayer for protection during the coming night. Evensong has an equivalent morning service called Matins.
Henry VIII became head of the Church of England around 1534 as a result of not being allowed by the Pope to divorce Catherine of Aragon. Because he had fallen out with the Roman Catholic Church, England became Protestant. New services were written by Archbishop Cranmer: in English rather than Latin, so that the people could understand them. Evensong was one such service, first published in the Book of Common Prayer of 1549. After that, England went through phases of religious uncertainty, so the version used today comes from the 1662 edition2.
Evensong was substituted by Archbishop Cranmer for two Catholic services: Vespers and Compline. It is usually sung3 at around 5.00pm, and lasts for around 45 minutes.
Evensong consists of Bible readings, psalms, prayers and two canticles4. There is a Bible reading from both the old and new testaments. At Evensong, the canticles are the 'Magnificat'5 and the 'Nunc Dimittis'6. Occasionally Psalm 98, 'Cantate Domino', is used in place of the 'Magnificat'; and Psalm 67, 'Deus Misereatur', for the 'Nunc Dimittis': however, this is rare, and is not permitted on the days when these psalms would be sung during the normal course of the service.
The choir sing some of the prayers, called the responses, both the canticles, and also an anthem7. The choir also sing the psalms8, usually in a style called Anglican Chant. Evensong is in English, but on occasion the anthem may be in Latin.
There are many different settings for the music at Evensong. These have been written predominantly by English composers, as Evensong is an Anglican service. At Evensong, the responses are always set by a different composer to the Magnificat and Nunc Dimmitis. Notable composers of music for evensong include Charles Villiers Stanford and Herbert Howells.
Evensong as a service is declining in popularity, and is rarely sung every day except at cathedrals. This is a shame because lots of beautiful music has been written for use at the service, and it is a tradition dating back 450 years in the Church of England.