The cardinals -- at least, those under 80 years old -- vote for as long as it takes to elect Pope Francis' successor.

The death of Pope Francis this month at the age of 88 set off grief and mourning around the world — along with a complex process to find a successor. Francis’ successor will be selected at a conclave that will begin May 7,

Cardinals will gather for the papal conclave — the centuries-old tradition through which a new head of the Catholic Church is elected — starting on May 7.