A liturgy is the customary public worship done by a specific religious group, according to their particular traditions. The word may refer to an elaborate formal ritual such as the Eastern Orthodox Divine Liturgy and Catholic Mass, or a daily activity such as the Muslim salat (see Oxford Dictionary of World Religions, p.582 - 3) and Jewish shacharit. As a religious phenomenon, liturgy is a communal response to the sacred through activity reflecting praise, thanksgiving, supplication, or repentance. Ritualization may be associated with life events such as birth, coming of age, marriage, and death. It thus forms the basis for establishing a relationship with a divine agency, as well as with other participants in the liturgy. Methods of dress, preparation of food, application of cosmetics or other hygienic practices are all considered liturgical activities. Repetitive formal rites, in some ways similar to liturgies, are natural and common in all human activities such as organized sports venues.
The word comes from the Classical Greek word λειτουργία (leitourgia) meaning "public work". In the Greek city-states, it had a different sense: some public good which a wealthy citizen arranged at his own expense, either voluntarily or by law. At Athens, the Assembly assigned liturgies to the wealthy, and there was a law by which any man who had been assigned a liturgy while a richer man had none could challenge him either to undertake the liturgy or to exchange property with him.
The church use of the term comes from its frequent and historic use in the Greek text of the New Testament (eg Acts 13:2). It referred to a public and deliberate, well-defined ceremony. It is often translated as "minister" or "worship" in English language Bibles.
Not infrequently in Christianity, a distinction is made between "liturgical" and "non-liturgical" churches based on the elaboration and/or antiquity of the worship, but this obscures the universality of public worship as a religious phenomenon. Thus, even the open or waiting worship of Quakers is liturgical, since the waiting itself until the spirit moves individuals to speak is a prescribed form of Quaker worship, sometimes referred to as "the liturgy of silence." Typically in Christianity, however, the term "the liturgy" normally refers to a standardized order of events observed during a religious service, be it a sacramental service or a service of public prayer.
As Peter Paul S.G. Kabigting explanation Liturgy defined as "public duty".