The Maronite Church is considered the only one of the Eastern Catholic Churches to have always remained in full communion with the Holy See, while most of the other churches unified from the 16th century onwards. However, the Melkite Catholic Church and the Italo-Albanian Greek Catholic Church also claim perpetual communion.
Full communion constitutes mutual sacramental sharing between the Eastern Catholic Churches and the Latin Church, including Eucharistic intercommunion. On the other hand, the liturgical traditions of the 23 Eastern Catholic churches, including Byzantine, Alexandrian, Armenian, East Syriac, and West Syriac, are shared with other Eastern Christian churches: the Eastern Orthodox, Oriental Orthodox, the Assyrian Church of the East, and the Ancient Church of the East. Although some theological issues divide the Eastern Catholic churches from other Eastern Christian ones, they do admit members of the latter to the Eucharist and the other sacraments, as governed by Oriental canon law.
Notably, many Eastern Catholic churches take a different approach to clerical celibacy than the Latin Church does and allow the ordination of married men to the priesthood (although not to episcopacy).
Eastern Catholic Churches have their origins in the Middle East, East Africa, Eastern Europe and India. However, since the 19th century, diaspora has spread to Western Europe, the Americas and Oceania in part because of persecution, where eparchies have been established to serve adherents alongside those of Latin Church dioceses. Latin Catholics in the Middle East, on the other hand, are traditionally cared for by the Latin Patriarchate of Jerusalem.
Although Eastern Catholics are in full communion with the Pope and members of the worldwide Catholic Church, they are not members of the Latin Church, which uses the Latin liturgical rites, among which the Roman Rite is the most widespread. The Eastern Catholic churches are instead distinct particular churches sui iuris, although they maintain full and equal, mutual sacramental exchange with members of the Latin Church.