Cardinal Robert Prevost has been announced as the new pontiff and has chosen the name Pope Leo XIV.
There are no written rules or official criteria for a pope's name, but they choose names that have meaning in the Catholic tradition.
The significance of a pope's nameThe name a new pope chooses will "indicate a certain spirit and direction and vision of the new pope," said Dennis Doyle, a theologian and professor emeritus of religious studies at the University of Dayton.
"The first thing that you would look for would be, which popes had that name before?" he said. "That would signify something about the direction that the pope wants to take."
Leo has been chosen 13 times before. The last, Pope Leo XIII, was the head of the church between 1878 and 1903.
Pope Francis, whose birth name was Jorge Mario Bergoglio, chose a papal name that hadn't been chosen by a pope before, so in his case, "you have to ask, well, are there any biblical figures or people in the tradition who have had that name?"
For Francis, it was Saint Francis of Assisi, known for his charity and simplicity.
What are the most common papal names?The names most used by popes have been:
John: 23 timesBenedict: 16 timesGregory: 16 timesClement: 14 timesLeo: 14 timesInnocent: 13 timesPius: 12 times"There could be more than one reference in the name that the pope chooses," Doyle explained.
For example, Pope Benedict XVI paid homage to Benedict XV, who led the church during World War I, but also to St. Benedict of Nursia, who founded the Benedictine Order and influenced the spread of Christianity throughout Europe.
The name John, the most popular, could refer back to the Gospel of John, which is one of "the most loved of the gospels," Doyle said. It can also refer to St. John the Baptist, the prophet who baptized Jesus.
Have popes always changed their names?Not every pope in history has changed his name. Out of 266 popes, 129 have chosen new names, according to Vatican News.
The practice became more ingrained around the 11th century, a period of German popes who chose names of early church bishops out of "a desire to signify continuity," Rev. Roberto Regoli, a historian at Rome's Pontifical Gregorian University, told The Associated Press.
For many centuries, new popes tended to choose the name of the pope who had elevated them to cardinal.
Only starting in the mid-20th century did new popes begin to choose names signaling the aim of their papacy, Regoli said.
Names never chosen by a popeSome biblical names that haven't been used by a pope are Joseph, James and Andrew.
Popes also have not chosen the name Peter, out of respect for St. Peter, a disciple of Jesus who is recognized as the first pope, experts say.
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Nicole Brown Chau