The
Eastern Orthodox Church, officially the
Orthodox Catholic Church, and also called the
Greek Orthodox Church or simply the
Orthodox Church, is the second-largest Christian church, with approximately 230 million baptised members. It 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 head of the Catholic Church. Nevertheless, the Ecumenical Patriarch of Constantinople is recognised by them as
primus inter pares, a title formerly given to the patriarch of Rome. 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.