Francis’ successor will be selected by cardinals at the conclave that began on May 7. Cardinals, known as the “princes of the church,” rank just below the pope in the Roman Catholic Church; together, they are known as the College of Cardinals. When a pope dies, the college chooses a successor.

Vatican’s medieval walls for the start of a conclave to elect a successor to Pope Francis. Here’s what to know.

Over the coming days, eyes will search for the billowing white smoke that signals Habemus Papam: “We have a pope.”