The Greek Orthodox Church, also known as the Eastern Orthodox Church, is the second-largest Christian denomination in the world after the Catholic Church. It is a self-governing body within the larger communion of Orthodox Christianity, which is divided into several national churches. Synonyms for the Greek Orthodox Church include the Orthodox Church, the Eastern Orthodox Church, the Greek Orthodox Patriarchate, and the Hellenic Orthodox Church. These terms all refer to the same religious institution, which traces its roots back to the early Christian Church in the Mediterranean region and has a strong presence in Greece, Russia, and other Eastern European countries.