From Orthodox Wiki, a great source for Orthodoxy:
The Orthodox Church is the one Church founded by Jesus Christ and his apostles, begun at the day of Pentecost with the descent of the Holy Spirit in the year 33 A.D. It is also known (especially in the contemporary West) as the Eastern Orthodox Church or the Greek Orthodox Church. It may also be called the Orthodox Catholic Church, the Orthodox Christian Church, the one, holy, catholic, and apostolic Church, the Body of Christ, the Bride of Christ, or simply the Church.
The bishops of the Orthodox Churches trace unbroken succession to the very apostles themselves, therefore ultimately receiving their consecrations from our Lord Jesus Christ. All the bishops of the Eastern Orthodox Churches, no matter their titles, are equal in their sacramental office. The various titles given to bishops are simply administrative or honorific in their essence. At an ecumenical council, each bishop may cast only one vote, whether he is the Ecumenical Patriarch or simply an auxiliary bishop without a diocese. Thus, there is no equivalent to the Roman Catholic papacy within the Eastern Orthodox Churches.
As with its Apostolic succession, the faith held by the Church is that which was handed by Christ to the apostles. Nothing is added to or subtracted from that deposit of faith which was “handed once for all to the saints” (Jude 3). Throughout history, various heresies have afflicted the Church, and at those times the Church makes dogmatic pronouncements (especially at ecumenical councils) delineating in new language what has always been believed by the Church, thus preventing the spread of heresy and calling to repentance those who rend asunder the Body of Christ. Its primary statement of faith is the Nicene-Constantinopolitan Creed.”