Pope once meant any senior bishop; Rome only claimed it later
The title comes from the Greek pappas, father, and early Christians in the East gave it to bishops generally. The first known use honoured a patriarch of Alexandria, Heraclas. Only under Leo I in the fifth century did the West reserve it for Rome's bishop, and that rule became official in the 11th century.
Today the pope is bishop of Rome and head of the Catholic Church, also styled supreme or Roman pontiff. Catholic teaching roots his primacy in Saint Peter, whom Jesus called the rock of the Church and entrusted with the keys of heaven. The office is the papacy; its jurisdiction is the Holy See, from the Latin word for a seat or chair, and it counts as a sovereign entity in international law, based in Vatican City, an enclave inside Rome created by the 1929 Lateran Treaty with Fascist Italy.
Early history is murkier than tradition suggests. Irenaeus, writing around 180 AD, believed Peter founded and organised the Roman church, and an epistle traditionally credited to Clement of Rome around 96 praised Peter and Paul as heroes. Many scholars accept that Peter died in Rome under Nero, but some argue for Palestine, and others note that a single ruling bishop in Rome may not have emerged until the middle of the second century. Before then, overlapping bishops and presbyters seem to have led congregations.
Authority grew in steps. In 195 Victor I excommunicated the Quartodecimans, who kept Easter on the date of Passover, and Sunday Easter eventually won out. After the Western empire fell, popes supplied continuity; Gregory I, from an old senatorial family, ran the church with Roman sternness. When Leo III crowned Charlemagne in 800, he set the precedent that no Western emperor would reign uncrowned by a pope.
From the 8th century until 1870, popes also governed the Papal States. Their earthly power then shrank, while spiritual claims hardened: 1870 brought the dogma of infallibility for rare ex cathedra definitions of faith or morals. The office still carries great weight, spiritual and diplomatic, among roughly 1.4 billion Catholics, and it oversees the largest non-government network of schools, health care and charities anywhere.
Source: Pope
