Who could be the next Pope - and how does the Conclave keep it a secret?

More than 100 cardinals eligible to vote have gathered in the Sistine Chapel. They will be sealed off from the outside world until a successor to Pope Francis is chosen.

Of the 252 total cardinals, only those under age 80 can vote. The eligible cardinals break down regionally with 52 from Europe, 23 from Asia, 20 from North America, 17 each from Africa and South America, and four from Oceania. Italy has the highest number of voting cardinals with 17, followed by the U.S. with 10 and Brazil with seven. The UK has three.

Before entering conclave, each cardinal swears an oath of secrecy, with excommunication as the penalty for revealing what happens inside. They also surrender their mobile phones and won’t get them back until a new pope is elected.

Cardinal Kevin Farrell, serving as Camerlengo, is overseeing the process until a new pontiff is chosen. A two-thirds majority is required to elect the next leader of the Catholic Church.

As tradition dictates, black smoke will signal a failed vote, while white smoke - and now, the ringing of St. Peter’s Basilica bells - will announce a successful election. Special chemicals have been used since 1963 to make the smoke more visible.

These are the leading candidates to become the next Pope:

Pietro Parolin (Italy) - Vatican secretary of state

Luis Antonio Tagle (Philippines) - Cardinal bishop of San Felice da Cantalice a Centocelle

Pierbattista Pizzaballa (Italy) - Latin patriarch of Jerusalem

Fridolin Ambongo Besungu (Congo) - Archbishop of Kinshasa

Angel Fernandez Artime (Spain) - Pro-prefect of the Dicastery for Institutes of Consecrated Life

Peter Erdo (Hungary) - Former president of Council of Bishops’ Conferences of Europe