It is one of the three main branches of Christianity, known for its continuity with the Apostolic Church, its liturgical traditions, and regional church organization. The Eastern Orthodox Church emphasizes its orthodoxy and apostolic inheritance, and has its own theology and liturgical system. Originating from the eastern provinces of the Roman Empire, mainly distributed in countries such as Greece, Russia, Ukraine, Serbia, etc., the number of believers exceeded 200 million. The governance structure of the church is characterized by autonomous churches and episcopal conferences, among which the Ecumenical Patriarch of Constantinople and the Patriarchs of Moscow and all of Russia are the most important leaders.