It is now the duty of 120 cardinals to decide who will head the millions of Catholics around the globe.
The influential College of Cardinals must now meet in Rome and choose the next Pope in a voting tradition that dates back almost 1,000 years.
John Paul II revised the procedures in 1996 and among the changes was the instruction that his successor can be elected by a simple two-thirds majority.
In the meantime, the Camerlengo, or chamberlain of the Holy Roman Church, Cardinal Eduardo Martinez Somalo, becomes an interim administrator, whose first job it is to decide the pope is dead in the presence of the Papal Master of Ceremonies and other key members of the Papal Household.
Traditionally, this is done by tapping the Pope on the forehead with a silver hammer and calling out his baptismal name three times. However, the Cardinal is more likely to rely on doctors.
The silver hammer would then be used to smash the Pope’s Fisherman’s Ring, to make sure no instructions can be given under his seal.
The Cardinal Vicar for Rome is then informed and he confirms the death to Rome and the world.
The chamberlain then arranges for the body to be removed and locks up the pontiff’s apartment at the Vatican to safeguard his possessions.
Nine days of official mourning are declared and the burial usually takes place in St Peter’s Basilica between the fourth and sixth day.
Since 1059, the selection of the next head of the Catholic church has been reserved to the College of Cardinals, whose members are appointed by the Pope.
The dean appointed in 2002 is Cardinal Joseph Ratzinger, a former archbishop of Munich. His role is to inform other cardinals, heads of state and ambassadors accredited to the Holy See.
In 2003 Pope John Paul II announced 30 new cardinals, including the Archbishop of St Andrew’s and Edinburgh, Keith O’Brien.
He becomes only the second British member of the college along with the Archbishop of Westminster, Cardinal Cormac Murphy-O’Connor.
The additions allow for the required number of 120 cardinals, aged under 80 and from all over the world, to vote. Those aged over 80 are not deemed eligible.
The college becomes immediately responsible for the day-to-day running of the Catholic church as Vatican offices are suspended but it is forbidden to take any decisions that would normally be reserved for the Pope.
Their key priority is to select the next pontiff and, following the death, the cardinals have up to 15 days to gather in Rome for the start of the election process.
Their coming together is known as the Conclave – from the Latin cum clave, literally meaning “with a key” in reference to them being locked in the Apostolic Palace until they produce a result.
Under the new 1996 regulations, the cardinals will be housed in a new building inside the Vatican’s walls called the Domus Sanctae Marthae (St Martha’s House).
They will move from there to the Papal Palace and the Sistine Chapel for the actual voting beneath Michelangelo’s fresco of the Last Judgment.
Throughout the process they are sworn to secrecy and forbidden to speak to anyone not involved in the election. Any breaches could result in their excommunication.
The cardinals wear a traditional black cassock with piping and red sash, a skull-cap, pectoral cross and ring throughout the process.
The 1996 voting rules now allow for just one method of selection, by two-thirds majority.
It replaces the traditions either of cardinals agreeing to one name without prior arrangement, which has never happened, or by compromise, which would be resolved either by a majority plus one, a ballot between the two strongest candidates or the decision of a small number of delegated cardinals.
The first vote is held on the afternoon of the first day if possible and there are then two ballots each morning and each afternoon thereafter until a result is declared.
Each cardinal enters a name on a special ballot paper and then, in order of precedence, puts it in a receptacle on an altar.
Three chosen cardinals, known as scrutineers, go through the votes one by one and announce the name on each paper.
The names are counted and if a name has received two-thirds of the votes, the Pope has been elected.
If the first ballot does not produce a result, the process is repeated for three days, after which there is a day’s rest for prayer, reflection and informal discussions.
The voting then begins again for a series of seven more ballots and then another break.
The process is repeated twice more and if there is still a stalemate, the Chamberlain will declare a result can come from an absolute majority or by a vote on the two names that received the largest number of votes in the last ballot.
The candidate is then asked if he accepts and what name he wishes to take.
John Paul II was elected on the eighth ballot.
Tradition dictates that once a Pope has been elected, white smoke will billow from the Vatican chimney – representing the burning of the ballot papers.
During the election of John XXIII, in 1958, Vatican Radio mistakenly informed the world one day early that a Pope had been elected.
Electronic signals of black and white replaced the smoke during the election of Paul VI in 1963 but it is believed there will be a return to tradition for the next Conclave.
If the person elected is not already a bishop, he shall be immediately ordained and becomes the Bishop of Rome.
He is then announced to the people in St Peter’s Square.
There is no coronation ceremony, but the pontificate is inaugurated at a ceremony in St Peter’s, usually within a matter of days.