A response is the second half of one of a set of preces

Preces

Preces are, in liturgical worship, short petitions that are said or sung as versicle and response by the officiant and congregation respectively...

, the said or sung answer by the congregation or choir

Choir

A choir, chorale or chorus is a musical ensemble of singers. Choral music, in turn, is the music written specifically for such an ensemble to perform.A body of singers who perform together as a group is called a choir or chorus...

 to a versicle

Versicle

A versicle is the first half of one of a set of preces, said or sung by an officiant or cantor and answered with a said or sung response by the congregation or choir...

 said or sung by an officiant

Officiant

An officiant is someone who officiates at a service or ceremony, such as marriage, burial, or namegiving/baptism. Officiants may be ordained by any denomination as members of their clergy, or by secular/Humanist or interfaith/interspiritual religious bodies...

 or cantor

Cantor (church)

A cantor is the chief singer employed in a church with responsibilities for the ecclesiastical choir; also called the precentor....

. In the following opening of the Anglican

Church of England

The Church of England is the officially established Christian church in England and the Mother Church of the worldwide Anglican Communion. The church considers itself within the tradition of Western Christianity and dates its formal establishment principally to the mission to England by St...

 service of Evening Prayer

Evening Prayer (Anglican)

Evening Prayer is a liturgy in use in the Anglican Communion and celebrated in the late afternoon or evening...

 according to the Book of Common Prayer

Book of Common Prayer

The Book of Common Prayer is the short title of a number of related prayer books used in the Anglican Communion, as well as by the Continuing Anglican, "Anglican realignment" and other Anglican churches. The original book, published in 1549 , in the reign of Edward VI, was a product of the English...

(BCP), the first line is the versicle and the second is the response.

O: O Lord, open thou our lips

P: And our mouth shall shew forth thy praise.

In some liturgical book

Liturgical book

A liturgical book is a book published by the authority of a church, that contains the text and directions for the liturgy of its official religious services.-Roman Catholic:...

s (such as hymnal

Hymnal

Hymnal or hymnary or hymnbook is a collection of hymns, i.e. religious songs, usually in the form of a book. The earliest hand-written hymnals are known since Middle Ages in the context of European Christianity...

s or breviaries

Breviary

A breviary is a liturgical book of the Latin liturgical rites of the Catholic Church containing the public or canonical prayers, hymns, the Psalms, readings, and notations for everyday use, especially by bishops, priests, and deacons in the Divine Office...

) the symbol "R/" or "℟" is used to denote a response.

There are many choral settings of the responses for BCP Evensong. Notable ones include those by Thomas Tomkins

Thomas Tomkins

Thomas Tomkins was an English composer of the late Tudor and early Stuart period. In addition to being one of the prominent members of the English madrigal school, he was a skilled composer of keyboard and consort music, and the last member of the English virginalist school.-Life:Tomkins was born...

, William Smith

William Smith (composer)

William Smith was an English composer from the city of Durham. He is chiefly known for his set of choral responses for the Anglican liturgy of Evening Prayer....

, Richard Ayleward

Richard Ayleward

Richard Ayleward was an English composer and musician. He was born the son of a canon in Winchester Cathedral and, upon the English Restoration, was appointed organist and choir master of Norwich Cathedral....

, Bernard Rose

Bernard Rose (musician)

Bernard William George Rose, OBE was variously a student at the Royal College of Music 1933-1935, organist, soldier, and composer...

, and Humphrey Clucas

Humphrey Clucas

Humphrey Clucas is a British composer, singer and author.Clucas read English at King’s College, Cambridge, where he was a choral scholar...

.