The Eastern Catholic Churches are autonomous, self-governing particular churches in full communion with the Pope.

Together with the Latin Church, they make up the Catholic Church as a whole.

They preserve many centuries-old Eastern liturgical, devotional, and theological traditions, shared in most cases with the various other Eastern Christian churches with which they were once associated, such as the Eastern Orthodox Church and Oriental Orthodox Church.Some theological issues (primarily, though not exclusively, regarding the role and extent of the authority of the Bishop of Rome) divide them from their counterparts of similar traditions but not in communion with Rome.

Accordingly, they admit members of such churches to the Eucharist and the other sacraments only in the circumstances indicated in canon law.

Historically, Eastern Catholic Churches are located in Eastern Europe, the Middle East, North Africa and India.

Due to migration they are now also in Western Europe, the Americas and Oceania, where eparchies have been established alongside the Latin dioceses.The terms Byzantine Catholic and Greek Catholic are used of those who belong to Churches that use the Byzantine Rite.

The terms Oriental Catholic and Eastern Catholic and Eastern Rite Roman Catholic include these, but are broader, since they also cover Catholics who follow the Alexandrian, Antiochian, Armenian and Chaldean liturgical traditions.