Eastern Orthodox Christians are members of the Eastern Orthodox Church, one of the oldest branches of Christianity. This tradition emphasizes the importance of the Holy Tradition, which includes the teachings of the Church Fathers and the decisions made by the Ecumenical Councils. The Eastern Orthodox Church is known for its rich liturgical life, including the celebration of the Divine Liturgy and various sacraments. The Eastern Orthodox Church is organized into several autocephalous (independent) churches, each led by a bishop. Major centers of Eastern Orthodoxy include the Patriarchate of Constantinople, the Russian Orthodox Church, and the Greek Orthodox Church. Eastern Orthodox Christians celebrate their faith through a variety of customs, including the use of icons and the observance of the liturgical calendar.