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The Next Era - On Tuesday, 115 cardinals of the Holy Roman Church will convene in the Sistine Chapel in Vatican City for the Conclave, the secret ceremony where the next pope is elected as the leader of some 1.2 billion Catholics around the world. Keep reading for a primer on how the process of selecting a pope comes together. — Britt Middleton  (Photo: REUTERS/Ali Jarekji)

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Pope Benedict XVI Says Farewell - Pope Benedict XVI, born Joseph Aloisius Ratzinger, was the first pope to join Twitter, and made history again on Feb. 28 when he resigned from his post. The 85-year-old religious leader is the first pope to resign in 600 years. (Photo: Franco Origlia/Getty Images)

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Who Can Vote  - The term "conclave" stems from the Latin phrase "with a key," referring to how the cardinals are locked inside the Vatican, which is the administrative center of the Roman Catholic Church, during the process. To be eligible, each cardinal's name has to have been previously publicized. Each member must be under the age of 80 by Feb. 28, the day the papal seat became vacant. (Photo: Franco Origlia/Getty Images)

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Where Does This Takes Place? - The Vatican makes up Rome's Vatican City and serves as the official residence of the pope. Vatican City is also home to many famous museums and landmarks, including Michelangelo's Sistine Chapel and the Vatican Gardens. (Photo: AP Photo/L'Osservatore Romano, ho)

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Where Do the Cardinals Vote? - Each conclave, the cardinals cast their ballots at the historic Sistine Chapel, under Michelangelo’s iconic frescoes. The chapel has been transformed for the occasion, including the addition of two stoves and chimneys that will signal with black or white smoke once they cardinals have come to a decision. (Photo: AP Photo/L'Osservatore Romano, ho)

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Where Are the Cardinals Housed? - During the process, the cardinals stay in what is called "Martha House," a Vatican guest house run by nuns.  (Photo: Christopher Furlong/Getty Images)

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The Role of Secrecy and Gender Rules - The cardinals are forbidden to communicate with anyone from the outside world until the new pontiff is chosen. Should a cardinal break this rule, he will be excommunicated. A woman cannot serve as pope because the candidate must be an ordained priest, and under Catholic doctrine, women are barred from doing so.  (Photo: AP Photo/Alessandra Tarantino)

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Black and White Smoke and Balloting - White smoke will plume from the chimney of Sistine Chapel after the pontiff is confirmed, whereas black smoke signals more deliberation is needed. Up to four ballots are cast each day until a two-thirds majority is reached. On the fourth day, if no majority is reached, the cardinals must take a break for prayer. (Photo: Peter Macdiarmid/Getty Images)

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Africa's "Great Hope" - Cardinal Peter Turkson of Ghana has been called the leading African candidate for pope. The 64-year-old heads the Vatican's peace and justice office and has raised awareness about African poverty, yet drew criticism for supporting the church's disapproval of condom usage in the face of staggering HIV/AIDS levels across Africa. (Photo: AP Photo/Domenico Stinellis)

Photo By AP Photo/Domenico Stinellis

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Other Notable Candidates - From the U.S., Cardinals Timothy Dolan and Sean O’Malley have also been considered as strong candidates for the position. However, according to a top secret Vatican document published last year by an Italian newspaper, Benedict XVI was secretly planning his succession and had chosen Cardinal Angelo Scola of Milan to replace him. (Photos from left: Darren McCollester/Getty Images, Franco Origlia/Getty Images)