To understand what an Eastern Catholic Church is, it helps to take a page from the history of liturgy.

For nearly a thousand years after the Apostles dispersed in every direction, “preaching the gospel to the whole creation,” the dominant form of public prayer, or liturgy – from the Greek leitourgia, “public service” – was not the Roman version of the Mass so familiar in our day. The reason for this is simple. The world was less systematized then, and there was no one dominant form of liturgy. In the first centuries of Christianity, there were no less than five thriving centers of influence – Antioch, Alexandria, Rome, Jerusalem, and eventually, Byzantium. Byzantium, renamed Constantinople by Roman emperor Constantine in 330 AD, was the capital of the Eastern portion of the Roman Empire.