Following the death of a pope, the cardinals of the Roman Catholic Church meet in a session known as a conclave to elect a successor.
The conclave, derived from a Latin word meaning locked together, must begin between 15 and 20 days following a pope's death.
The tradition of isolating the cardinals developed following a nearly three-year deadlock over a papal election in the 13th century. Church members, tired of waiting, locked the cardinals in a palace and removed the roof, forcing a quick election.
During the conclave, the 117 eligible cardinals gather in the Sistine Chapel to vote four times a day, twice each in the morning and evening. Every time there is no winner, an official burns the ballots with a special chemical to produce black smoke that rises from a chimney above the chapel.
When the cardinals succeed, only the ballots are burned, sending white smoke rising from the chimney and signaling to the world that the 1.1 billion-member Roman Catholic Church has a new pontiff.
A senior cardinal then steps out onto the central balcony in front of Saint Peter's Basilica and announces in Latin to thousands of the faithful assembled in the square below - "habemus papam," or we have a pope.
The new pontiff then steps out in his papal robes and gives the city and the world his first blessing.