How the Church elects a new pope
The most senior figures in the Catholic Church have begun the secretive process of electing a new pope following the shock resignation of Benedict XVI.
Pope Benedict stunned the world on a quiet Monday morning in February when he announced to cardinals in characteristically understated tones - in Latin - that he no longer had the strength to carry on his ministry and would therefore be resigning.
The Church found itself in uncharted waters: no pope had resigned in more than 600 years. But he received a cinematic send-off, being whisked away from the Vatican City to Castelgandolfo, where popes traditionally spend the summer months, by helicopter. His personal secretary wept and the papal apartments were sealed.
Meanwhile cardinals from around the world had begun to converge on Rome to see his final public appearances as pope and to start preparing for the conclave at which his successor will be elected.
While only cardinals under the age of 80 may vote in the conclave, all may take part in the preliminary discussions aimed at discerning what sort of pope the Church needs.
On Friday, after a week of General Congregations, the cardinals set a date for the conclave to start: Tuesday 12 March. The Vatican is likely to want a new pope by the start of Holy Week, the Church's busiest week of the year, marked out by a series of high-profile liturgies followed by millions of Catholics around the globe.
This afternoon the cardinal-electors filed into the Sistine Chapel. They are all staying at the St Martha Residence and are taken by bus to and from the conclave to prevent them from having contact with the outside world.
In recent days and weeks the historic chapel has been fitted with a false floor and anti-bugging devices to prevent the contents of the discussions being leaked. In addition two stoves and a chimney have been installed: one stove to burn ballot papers and the other to emit either black smoke to signal that a vote has proved inconclusive or white smoke to indicate a clear winner.
The electors one by one swore an oath of secrecy in Latin.
Mgr Guido Marini, papal master of ceremonies, called out the words 'Extra omnes' - 'Everybody out' - and the chapel doors were locked to outsiders.
Today the elderly Maltese cardinal Prosper Grech was to give a meditation.
Leading down from the altar are 12 long wooden tables where the cardinals will prepare their ballots. They sit on cherry wood chairs, each engraved with the name of the cardinal-elector who occupies it. The cardinals cast their votes in front of Michelangelo's fresco of The Last Judgment on the wall of the altar.
The cardinals don't have to vote today, but if they do, we may see a smoke signal at around 7pm local time. Assuming a pope is not elected today, from tomorrow there will be four votes per day until a clear winner is found. The second smoke signal will be sent at around noon tomorrow.
The 2005 conclave that elected Pope Benedict took just 24 hours. He was elected on the fourth ballot. However this time the process could take longer because there is no clear front-runner.
During the voting, each cardinal has a ballot paper inscribed with the words: 'Eligo in summen pontificem' - 'I elect as Supreme Pontiff'. He writes his choice on a rectangular piece of paper, preferably in handwriting that is not identifiable as his own.
Each voter folds over his ballot paper twice. One by one they approach the altar holding their ballot aloft. Each cardinal declares: 'Testor Christum Dominum, qui me iudicaturus est, me eum eligere, quem secundum Deum iudico eligi debere'. (I call as my witness Christ the Lord, who will be my judge that my vote is given to the one who, before God, I think should be elected.) He places the paper on a saucer before tipping it into a silver oval urn, before bowing and returning to his seat.
Cardinals who are unable to walk to the altar pass their vote to a scrutineer, who drops it in the urn for them.
If there are cardinals who are too sick to vote, three cardinals designated as 'infirmarii' collect their ballot papers from their bedsides.
Three cardinals designated as scrutineers count the ballots, one of whom pierces each with a needle through the word 'Eligo', binding them together. Three revisers check the counting. The ballots and any other handwritten notes are placed in a cast-iron stove and burned with a special chemical.
All eyes - and a Vatican Television camera - will be on the 6ft copper chimney that has been installed atop the Sistine Chapel to pipe out puffs of smoke that tell the world if there is a new pope or not: black smoke indicates no clear winner emerged from the vote; white smoke shows a new pope has just been elected.
There is no maximum time limit - the conclave lasts until a new pope is elected. But the Vatican very much hopes for a new pope by Easter, 31 March. Effectively, to preside at the Holy Week liturgies, he would have to be in place by Palm Sunday, 24 March - Sunday week.
Who are the most likely contenders to succeed Benedict XVI on the throne of St Peter? We guide you through the complex process of electing a new pope.
Who's in the frame?
Cardinal Angelo Scola, 71, Archbishop of Milan
The current front-runner according to many Italians. He is close to Pope Benedict and has an impressive curriculum vitae that includes serving as rector of the Lateran University and bishop in two previous dioceses, including as Patriarch of Venice. He is also one of the first priests to be ordained, ...
Cardinal Odilo Pedro Scherer, 63, Archbishop of São Paulo
The strongest Latin American candidate. Not only has he headed the largest diocese in the world's largest Catholic country since 2007, he also has sterling Roman credentials. German-Brazilian by birth, he obtained a licentiate and doctorate in theology at the Gregorian University and spent several ...
Cardinal Peter Turkson, 64, president of the Pontifical Council for Justice and Peace
A front-runner among the Africans. Born in Ghana, he is one of the few Africans to have undertaken doctoral studies at the Pontifical Biblical Institute in Rome. He completed his basic theology at a seminary run by the Conventual Franciscans in New York and then taught in a seminary in his homeland. ...
Cardinal Christoph Schönborn OP, 68, Archbishop of Vienna
A theologian of the Dominican tradition who studied in Paris and Germany. He is urbane and polyglot. When he became a young cardinal in 1998, he was considered one of the brightest among the conservatives in the college, but that was when there existed some notable moderate-to-progressives who ...
Cardinal Leonardo Sandri, 69
Has been described as an ideal Italian-Argentine candidate who would restore the order that has all but crumbled in the Roman Curia during the current pontificate. Currently prefect of the Congregation for the Oriental Churches, he is a lifelong papal diplomat with a pedigree from the Accademia ...
Cardinal Marc Ouellet SSP, 68
Has headed the Congregation for Bishops since June 2010. A French-Canadian, he joined the prestigious Sulpician teaching society shortly after priestly ordination and has spent most of his life as a seminary professor and rector. He worked in Colombia and Canada before going to Rome in 1997 ...
Cardinal Gianfranco Ravasi, 70
Became an instant hit when Benedict named him president of the Pontifical Council for Culture in 2007. A first-rate biblical scholar who has popularised Scripture studies through Italian television, radio and popular periodicals, he has spearheaded efforts to re-establish the prominent place ...
Cardinal João Braz de Aviz, 65, prefect of the Congregation for Religious
Has been in Rome since January 2011 and was previously Archbishop of Brasília. He was created a cardinal in January 2012. His predecessor at the Congregation for Religious, Cardinal Franc Rode, spoke of a "crisis" in religious life following the Second Vatican Council caused by liberalising ...
Cardinal John Onaiyekan, 69, Archbishop of Abuja, Nigeria
Created a cardinal in the consistory of November 2012, he holds a master's degree in Sacred Scripture from the Pontifical Biblical Institute and a doctorate in biblical theology at the Pontifical Urban University. He served as a seminary rector and was appointed a bishop in 1982. He is a national ...
Cardinal Luis Antonio Tagle, 55
Primate of the Philippines and Archbishop of Manila since October 2011, is a charismatic figure described by the Vatican commentator John Allen as "a genuine intellectual with a popular touch". Pope John Paul II appointed Tagle to the International Theological Commission, where he served from ...