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?