Liturgy is a term that refers to the prescribed order of worship used in many religions and churches. Certain Christian denominations follow a standard form of worship for their services which normally includes hymn singing, prayers, scripture readings, responsive readings, a creedal statement, the sermon, a confession of sins, Holy Communion, and a formal dismissal. Other denominations do not use the historic order of worship and are more spontaneous in their worship practices. These are called "non-liturgical" churches. They include the Baptist and Pentecostal churches and most non-denominational ones.
Churches in which a version of the traditional liturgy is used--such as the Eastern Orthodox, Roman Catholic, High Church Anglican, Lutheran, Methodist, Reformed and Presbyterian churches--are classified as "liturgical" in worship. In some of them the liturgical service is styled the Mass, a word that invokes the concept of the service as a ceremonial offering of a sacrifice to God.
The liturgy is sometimes set forth according to a book used by the congregation at worship. Examples are the Book of Common Prayer in the Anglican and Episcopal churches, Missals used by the Catholic churches, and Lutheran Service Books.