As the conclave to elect a successor to Pope Francis begins, cardinals will be voting multiple times per day until a two-thirds majority vote is reached.
People from all over the world will be watching the chimney on the roof of the Sistine Chapel for black or white smoke as the cardinals' votes are burned and a signal is sent to the public.
Black smoke means that a pope has not yet been elected.
When white smoke emerges, it means a new pope has been chosen.
But how do they make the coloured smoke? Watch the video to find out.
