Saint Peter was the first Pope. To him (who is also known as “the Prince of the Apostles”) Our Lord gave two main tasks: the so-called “power of the keys of the kingdom of heaven” (cfr Matthew 16,19) and the role of strengthening the other apostles, the original bishops (cfr Luke 22,31-32).
The “power of the keys” denotes the authority that Saint Peter was given, by divine mandate, to forgive sins (“binding and loosing”) and, by extension, to teach with authority about right doctrine (the Catholic faith) and about how we should act (morals).
In strengthening the other apostles, Saint Peter acted as a visible sign of unity to the whole community of believers, the Church. Right from the start of the Church’s life, we see how the other bishops deferred to St Peter’s authority on deciding upon important matters (cfr Acts 15,1-35).
The authority of Saint Peter is continued, through the Apostolic Succession, in the ministry of every subsequent Pope. As the Catechism reminds us, “this pastoral office of Peter and the apostles belongs to the Church’s very foundation and is continued by the bishops under the primacy of the Pope”. Every Pope, as Bishop of Rome and successor of Saint Peter, “is the perpetual and visible source and foundation of the unity both of the bishops and of the whole company of the faithful” (Lumen gentium 23).