After a week of meetings at the Vatican, the assembled Catholic cardinals have decided to start the secret ballot process for the next pope on Tuesday afternoon.
As we explained earlier, any cardinal under 80 can participate in the conclave. Since electing the next pope is pretty much the only item in the cardinal job description, they're expected to participate (cardinals can and often are, of course, assigned to other posts and dioceses in church leadership). For this conclave, 115 cardinal-electors will take part. Two eligible cardinals won't be there: Cardinal Keith O'Brien, who gave his resignation as Archbishop of St. Andrews and Edinburgh amid scandal, and Cardinal Julius Riyadi Darmaatmadja of Indonesia, who is in poor health.
Holy Week begins March 24, so the cardinals are going to attempt a quick conclave. After celebrating a morning Mass in St. Peter’s Basilica, the cardinal-electors will enter into the conclave and hold ballots, twice each morning and afternoon, until one candidate has a two-thirds majority, which in this conclave will be 77 votes. This is where the white and black smoke comes in: black smoke indicates that a ballot didn't result in a new pope, while white smoke means that someone has hit the two-thirds majority.
According to Reuters, the cardinal-electors will stay in a Vatican hotel while not actively voting, which is notably more comfortable from the past requirement that cardinals remain locked in areas around the Sistine Chapel until a new pope is elected. According to the Vatican, conclave participants won't be allowed phone calls, emails, or other external communications while the ritual is underway. Jamming devices, meanwhile, will minimize eavesdropping on the secret process.
Once the conclave reaches a two-thirds majority, the newly-elected pope will then accept his election, choose a new pope name, and don the pontifical robes before the choice is announced publicly.