The Eastern Orthodox Churches are a group of Christian denominations that share a common tradition and theology, rooted in the teachings of the early Church. They emphasize the importance of the sacraments, particularly the Eucharist, and maintain a rich liturgical life. The churches are organized into various national jurisdictions, such as the Greek Orthodox Church and the Russian Orthodox Church, each led by its own hierarchy of bishops. Eastern Orthodox Christianity traces its origins to the Byzantine Empire and the early Christian communities in the Eastern Mediterranean. It is characterized by its adherence to the Nicene Creed and the decisions of the Seven Ecumenical Councils. The churches value the continuity of faith and practice, preserving ancient traditions while engaging with contemporary issues.