What is the pope, and why is he called the Bishop of Rome?

The pope is the bishop of Rome and the head of the worldwide Catholic Church. The two titles fit together because, in Catholic teaching, he leads the whole Church by holding Rome's bishopric. From a Catholic viewpoint, his primacy comes from being the successor of Saint Peter, to whom Jesus is said to have given the Keys of Heaven and whom he named the "rock" on which the Church would be built.

The word itself is humbler than it sounds. "Pope" comes from a Greek word for "father", and in the early centuries it was used, especially in the East, for all bishops and other senior clergy. It became reserved in the West for the bishop of Rome around the time of Pope Leo I in the fifth century, and that reservation was made official only in the eleventh century.

Historians add some caution to the Catholic account. Many scholars agree that Peter was martyred in Rome under Nero, but some argue that the bishop's seat in Rome can be traced back no earlier than the third century. Irenaeus, a Church Father writing around 180, already believed that Peter had "founded and organized" the Church at Rome.

Over time the job grew far beyond religion. From the eighth century until 1870 the pope was also the ruler of the Papal States, and since 1929 he has headed the much smaller Vatican City State. Today the office is largely focused on religious matters. As of October 2026 the pope is Leo XIV, who was elected on 8 May 2025.