Divine Liturgy in the context of "Byzantine Rite"

The Eastern Orthodox Church, officially the Orthodox Catholic Church, and also called the Greek Orthodox Church or simply the Orthodox Church, is one of the three major doctrinal and jurisdictional groups of Christianity. As of 2012, it has approximately 300 million adherents and is the third largest religious community in the world after Catholics and Sunni Muslims. The Eastern Orthodox Church operates as a communion of autocephalous churches, each governed by its bishops via local synods. The church has no central doctrinal or governmental authority analogous to the pope of the Catholic Church. Nevertheless, the Ecumenical Patriarch of Constantinople is recognised by them as primus inter pares ('first among equals'), a title held by the patriarch of Rome prior to 1054. As one of the oldest surviving religious institutions in the world, the Eastern Orthodox Church has played an especially prominent role in the history and culture of Eastern and Southeastern Europe. Since 2018, there has been an ongoing schism between Constantinople and Moscow, with the two not in full communion with each other.

Eastern Orthodox theology is based on the Scriptures and holy tradition, which incorporates the dogmatic decrees of the seven ecumenical councils, and the teaching of the Church Fathers. The church teaches that it is the one, holy, catholic and apostolic church established by Jesus Christ in his Great Commission, and that its bishops are the successors of Christ's apostles. It maintains that it practises the original Christian faith, as passed down by holy tradition. Its patriarchates, descending from the pentarchy, and other autocephalous and autonomous churches, reflect a variety of hierarchical organisation. It recognises seven major sacraments (which are called holy mysteries), of which the Eucharist is the principal one, celebrated liturgically in synaxis. The church teaches that through consecration invoked by a priest, the sacrificial bread and wine become the body and blood of Christ. The Virgin Mary is venerated in the Eastern Orthodox Church as the Theotokos, which means 'God-bearer', and she is honoured in devotions.

Hagia Sophia, officially the Hagia Sophia Grand Mosque, is a mosque serving as a major cultural and historical site in Istanbul, Turkey. It was formerly a church (360–1453) and a museum (1935–2020). The last of three church buildings to be successively erected on the site by the Eastern Roman Empire, it was completed in AD 537, becoming the world's largest interior space and among the first to employ a fully pendentive dome. It is considered the epitome of Byzantine architecture and is said to have "changed the history of architecture". From its dedication in 360 until 1453 Hagia Sophia served as the cathedral of Constantinople in the Byzantine liturgical tradition, except for the period 1204–1261 when the Latin Crusaders installed their own hierarchy. After the fall of Constantinople in 1453, it served as a mosque, having its minarets added soon after. The site became a museum in 1935, and was redesignated as a mosque in 2020.

The current structure was built by the Byzantine emperor Justinian I as the Christian cathedral of Constantinople between 532–537 and was designed by the Greek geometers Isidore of Miletus and Anthemius of Tralles. It was formally called the Temple of God's Holy Wisdom, (Greek: Ναὸς τῆς Ἁγίας τοῦ Θεοῦ Σοφίας, romanized: Naòs tês Hagías toû Theoû Sophías) the third church of the same name to occupy the site, as the prior one had been destroyed in the Nika riots. As the episcopal see of the ecumenical patriarch of Constantinople, it remained the world's largest cathedral for nearly a thousand years, until the Seville Cathedral was completed in 1520.

Liturgy is the customary public ritual of worship performed by a religious group. As a religious phenomenon, liturgy represents a communal response to and participation in the sacred through activities reflecting praise, thanksgiving, remembrance, supplication, or repentance. It forms a basis for establishing a relationship with God or the divine.

Technically speaking, liturgy forms a subset of ritual. The word liturgy, sometimes equated in English as "service", refers to a formal ritual enacted by those who understand themselves to be participating in an action with the divine.

The Alexandrian rites are a collection of ritual families and uses of Christian liturgy employed by three Oriental Orthodox churches (the Coptic Orthodox Church, the Eritrean Orthodox Tewahedo Church, and the Ethiopian Orthodox Tewahedo Church), and by three Eastern Catholic Churches (the Coptic Catholic Church, the Eritrean Catholic Church, and the Ethiopian Catholic Church).

The Alexandrian rite's Divine Liturgy contains elements from the liturgies of Saints Mark the Evangelist (who is traditionally regarded as the first bishop of Alexandria), Basil the Great, Cyril of Alexandria, and Gregory of Nazianzus. The Alexandrian rites are sub-grouped into two rites: the Coptic Rite and the Ge'ez Rite.

Mass is the main Eucharistic liturgical service in many forms of Western Christianity. The term Mass is commonly used in the Catholic Church, Western Rite Orthodoxy, Old Catholicism, and Independent Catholicism. The term is also used in many Lutheran churches, as well as in some Anglican churches, and on rare occasion by other Protestant churches.

Other Christian denominations may employ terms such as Divine Service or worship service (and often just "service"), rather than the word Mass. For the celebration of the Eucharist in Eastern Christianity, including Eastern Catholic Churches, other terms such as Divine Liturgy, Holy Qurbana, Holy Qurobo and Badarak (or Patarag) are typically used instead.