In an unexpected move, Pope Benedict XVI -- born Joseph Ratzinger -- has announced that he is to resign. Benedict was elected pope in 2005 after the death of Pope John Paul II. We explore what the surprise announcement means for the Catholic Church.
Why has Pope Benedict XVI resigned?
In his statement, Pope Benedict -- who turns 86 in April -- said he had come to the certainty "that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry."
Vatican spokesman the Rev. Federico Lombardi said Pope Benedict had the right and potentially the duty to resign.
But he stressed that the pope's decision was not because of any external pressure.
Is the pope in poor health?
Lombardi told reporters the pope was not unwell.
"There isn't any disease specifically -- it's all to do with deterioration and weakness in his body, as the holy pontiff has said in his statement," he said.
Lombardi said the battery in the pope's pacemaker -- which he has had since he was a cardinal -- had been replaced in the last few months, but he stressed that it was a routine procedure.
When will he step down?
The pope said that he would step down at 8:00 p.m. on February 28, Rome time.
Lombardi said as far has he knew, the day was "just an ordinary day" without particular significance but that Pope Benedict might have chosen it to ensure a new pope was in place for Easter.
He said he understood the pope usually finished his working day at 8:00 p.m. which was why he had chosen that specific hour to step down.
Is it normal for popes to resign?
It is the first time a pope has resigned in nearly 600 years.
The last pope to resign was Pope Gregory XII in 1415. He stepped down to end the "Great Western Schism" -- during which there were rival claims to the papal throne.
In 1294, Pope Celestine V resigned after only five months, preferring the simple life of a monk to the majesty of being pope.
According to the National Catholic Weekly, modern popes have felt that resignation is unacceptable and could encourage factions within the church to pressure pontiffs to step down.
Canon law states that a resignation must be made freely and properly manifested and that the pope resigning must be of sound mind.
When will the next pope be elected?
A meeting of the College of Cardinals to elect the next pope will be held. The gathering is known as a "conclave."
Vatican spokesman Federico Lombardi said there would be elections some time in March and he anticipated that there would be a new pope before Easter.
Lombardi said Vatican scholars were studying the constitution to determine exactly when the conclave would begin.
What is the election process?
By law, the conclave begins in the Sistine Chapel. On that morning, the cardinals will celebrate the Votive Mass, "Pro Eligendo Papa." That afternoon, the cardinals begin the election process.