The death or resignation of a pope starts a conclave, a centuries-old ritual of electing a successor that involves sacred oaths, Latin chants and the piercing of ballots with a needle and thread after they have been cast and counted. Then they are burned to produce either the white or black smoke that signals if there is a new leader for the world’s 1.3 billion Catholics.

What is a conclave and how is a new pope chosen - AP explains

The death or resignation of a pope starts a conclave, a centuries-old ritual of electing a successor that involves sacred oaths, Latin chants and the piercing of ballots with a needle and thread after they have been cast and counted. Then they are burned to produce either the white or black smoke that signals if there is a new leader for the world’s 1.3 billion Catholics.