The Catholic Church is actually composed of 24 churches — one Latin (Roman), which comprises perhaps 98% of all Catholics worldwide, and 23 "Eastern" or “Oriental” churches. All recognize the authority of the papacy, but within the parameters of a shared creed, each church has its own forms of liturgy, devotions, and traditions. Each has its own hierarchy under a patriarch or archbishop, and distinctive Eastern legal canons. Liturgy, above all, plays a defining role for the identity of these churches.
All of these churches embody traditions and practices that are at least a millennium old, and are heirs to the original Christian tradition of a particular region. Many trace their origins back to the apostles or to apostolic times.
The term "Eastern" refers to the Eastern half of the Roman Empire, but these churches developed in regions from Egypt to Russia to India. After the great schism between East and West of 1054, most of the churches were aligned with Orthodoxy. Beginning in the late 16th century, some clergy and members of those churches united with the church of Rome. Today, all but two of these churches have counterpart Orthodox churches — e.g. the Ukrainian Catholic has a counterpart Ukrainian Orthodox church.
Each of the churches grew out of a particular geographic place and culture, and has been generally tied to strong nationalist sentiment, though these churches have now spread geographically to many parts of the globe.
Eastern Churches, listed below, are generally grouped in five liturgical traditions:
I. Alexandrian liturgical tradition, originating in Egypt:
- Coptic Catholic Church
- Eritrean Catholic Church
- Ethiopian Catholic Church
II. Antiochian liturgical tradition, originating in Antioch and West Syria:
III. Armenian liturgical tradition:
- Armenian Catholic Church
IV. Chaldean or East Syrian liturgical tradition, originating in Mesopotamia:
V. Byzantine or Constantinopolitan liturgical tradition, originating in Constantinople:
- Albanian Catholic Church
- Belarusian Catholic Church
- Bulgarian Catholic Church
- Croatian Byzantine Catholic Church or Croatian Greek Catholic Church
- Greek Catholic Church
- Hungarian Catholic Church
- Italo-Albanian Catholic Church
- Macedonian Catholic Church
- Melkite Greek Catholic Church
- Romanian Church United with Rome
- Russian Catholic Church
- Ruthenian Catholic Church
- Slovak Catholic Church
- Ukrainian Catholic Church