A versicle is the first 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...

, 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....

 and answered with a said or sung response

Response (liturgy)

A response is the second half of one of a set of preces, the said or sung answer by the congregation or choir to a versicle said or sung by an officiant or cantor...

 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...

. For example, 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 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...

, 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 "V" or "℣" is used.