Eastern Orthodox Church
The Orthodox Church is an international group of patriarchal, autocephalous and autonomous churches. Each church is independent in her internal organization and follows her own particular customs. However, all the churches are united in the same faith.
Each Church is led by a synod of bishops. The Ecumenical Patriarch of Constantinople is is regarded as "first among equals."
The Great Schism
The Great Schism is the title given to separation between the Western Church (the Roman Catholic) and the Eastern Church, (the Orthodox), which took place in the eleventh century.
By the ninth century legitimate differences were intensified by political circumstances, cultural clashes, papal claims, and the introduction in the West of the Filioque phrase into the Nicene Creed.