The member of the church hierarchy with the highest ordination, a successor of the Apostles. Since the consecration he has a sanctifying, teaching and governing duties which can be carried out only in the hierarchical community with the Head of the College of Bishops, the Roman Pontiff (pope).
According to the domain of authority, bishops are called diocesan - where they are managing the diocese (ordinaries) or titular, when they do not exercise power over any diocese. For help in priestly duties of the diocesan bishop, a coadjutor bishop (a successor) and an auxiliary bishop can be appointed. After reaching a certain age determined by the law (75 years), the bishop should retire, and become a senior bishop.