Pope Francis on Sunday promoted 17 Roman Catholic prelates from around the world to the high rank of cardinal, including 13 who are under 80 years old and thus eligible to succeed him one day.

Cardinals, who wear red hats and are known as "princes of the church," are the most senior members of the Roman Catholic hierarchy after the pope and serve as his principal advisers around the world and in the Vatican.

Naming new cardinals is one of the most significant powers of the papacy, allowing a pontiff to put his stamp on the future of the 1.2-billion-member global church.