VATICAN CITY - When the cardinal electors begin their conclave Tuesday, they will attend mass at St. Peter's Basilica, then proceed into the Sistine Chapel, when the doors will be shut before balloting begins.
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Inside, the 115 voting cardinals of the Roman Catholic Church -- those under 80 years old -- will take an oath of secrecy.
Then lots are drawn. Three cardinals will be selected to collect the ballots, three will be selected to count the votes and three will be selected to review the results.
On the ballots are the words, "eligo in summum pontificem." CNN said that means "I elect as supreme pontiff."
Each elector writes the name of one candidate on the lower half of the ballot and folds it in half. Cardinals are not allowed to vote for themselves.
In order of seniority, the cardinals take their ballots to the altar.
Once the ballots are counted, the results are read aloud.
More than a two-thirds majority is needed to declare a winner. In this case that's 77 votes.
If there is no winner, there's another vote. Cardinals will take two votes each morning and each afternoon until there's a winner.
The ballots are burned after each session in an incinerator inside the chapel, sending off a smoke signal.
If there's no winner, the ballots are burned with a chemical that gives off black smoke. That tells the crowd waiting in St. Peter's Square that a new pope has not yet been selected.
When there is a winner, the ballots are burned alone. That creates a white smoke -- a sign from the cardinals that they have chosen a new pope to lead the church.