When a new pope is elected, one of his first acts is to choose a papal name, a tradition that dates back to 533 AD when Pope John II changed his birth name Mercurius, which was associated with a pagan god

. This practice became standard by the 10th century and symbolizes a new mission or "second birth" as the leader of the Catholic Church

. There are no formal rules governing the choice of a papal name, but popes typically select a name with personal or historical significance

. The name often honors a saint, a previous pope they admire, or reflects the direction they wish their papacy to take. For example, Pope Francis chose his name in honor of St. Francis of Assisi, emphasizing humility and care for the poor

. John Paul II took his name to honor his immediate predecessor, John Paul I

. Popes avoid choosing the name "Peter" out of reverence for St. Peter, the first pope

. The chosen name is announced publicly from the balcony of St. Peter's Basilica with the famous phrase "Habemus papam" ("We have a pope")

. In summary, the pope’s name choice is a symbolic gesture reflecting personal devotion, historical continuity, or a statement about the priorities of his pontificate, without any strict rules but steeped in centuries of tradition