The Catholic Church follows an episcopal polity, led by bishops who have received the sacrament of Holy Orders who are given formal jurisdictions of governance within the church. There are three levels of clergy, the episcopate, composed of bishops who hold jurisdiction over a geographic area called a diocese or eparchy; the presbyterate, composed of priests ordained by bishops and who work in local diocese or religious orders; and the diaconate, composed of deacons who assist bishops and priests in a variety of ministerial roles. Ultimately leading the entire Catholic Church is the Bishop of Rome, commonly called the pope, whose jurisdiction is called the Holy See. In parallel to the diocesan structure are a variety of religious institutes that function autonomously, often subject only to the authority of the pope, though sometimes subject to the local bishop. Most religious institutes only have male or female members but some have both. Additionally, lay members aid many liturgical functions during worship services.