Many Christians affirm episcopal church government, rule by bishops, from the Greek episkopos, overseer, who ordain clergy, oversee dioceses, and are held by these traditions to stand in a ministry reaching back to the apostles. On this view the threefold ministry of bishops, priests, and deacons is the church's God-given order, and the bishop is the focus of unity and the guardian of teaching and sacrament within a region.
The polity is not uniform even among those who hold it. Roman Catholic structure places a single bishop, the Pope as bishop of Rome, in a position of universal jurisdiction over the whole church, a supreme authority the Eastern Orthodox and Oriental Orthodox communions do not recognize. Orthodoxy instead organizes itself as a communion of self-governing, autocephalous churches, Greek, Russian, Serbian, and others, each headed by its own senior bishop or patriarch, with the Ecumenical Patriarch of Constantinople honored as first among equals in ceremonial precedence but without Rome's kind of direct governing authority over the other churches. The two structures, one centralized under a single universal bishop, the other a federation of equal, independent episcopates in shared communion, represent genuinely different institutional answers to how bishops relate to one another across the whole church, not merely local variations on a single model.