The pope is the title given to the Bishop of Rome, who serves as the head of the Roman Catholic Church. According to Catholic tradition, Jesus made Peter, one of his disciples, the leader of his church and Peter later served as the first Bishop of Rome. Popes, as Peter's successors as Bishop of Rome, are the leaders of the church. Elected for life by senior bishops (the College of Cardinals), the pope exercises strong central authority. The doctrine of papal infallibility is the clearest expression of papal primacy, although it has only been invoked twice since its official definition in 1870. The pope is an object of shared identification for Catholics—a sign of the unity and universality of the Church around the world—as well as a focal point for criticism inside and outside the church. The papacy is currently held by Pope Francis, who succeeded Pope Benedict XVI in 2013.
The power of the papacy reached its zenith during the eleventh and twelfth centuries, when popes asserted temporal as well as spiritual authority and were key players in the politics of Europe. With the rise of powerful monarchies, the Protestant Reformation of the sixteenth century and the emergence of the modern nation state, the power of the papacy waned. Following the unification of Italy in the 1860s, the pope retreated to Vatican City, a sovereign city-state surrounded by the city of Rome. Since the Church's embrace of democracy and religious freedom with the Second Vatican Council (1962-1965), the pope has again emerged as an important figure world affairs. As the leaders of a global community that now includes more than one billion Catholics, popes since John XXIII (1958-1963) have spoken out on issues of war and peace, economic and social development, and interreligious dialogue. The global engagement of John Paul II is credited with helping to bring about the collapse of the Soviet Empire and the end of the Cold War.