Benedict issued the following statement.
I have convoked you to this Consistory, not only for the three canonisations, but also to communicate to you a decision of great importance for the life of the Church. After having repeatedly examined my conscience before God, I have come to the certainty that my strengths, due to an advanced age, are no longer suited to an adequate exercise of the Petrine ministry. I am well aware that this ministry, due to its essential spiritual nature, must be carried out not only with words and deeds, but no less with prayer and suffering. However, in today's world, subject to so many rapid changes and shaken by questions of deep relevance for the life of faith, in order to govern the bark of Saint Peter and proclaim the Gospel, both strength of mind and body are necessary, strength which in the last few months, has deteriorated in me to the extent that I have had to recognise my incapacity to adequately fulfill the ministry entrusted to me. For this reason, and well aware of the seriousness of this act, with full freedom I declare that I renounce the ministry of Bishop of Rome, Successor of Saint Peter, entrusted to me by the Cardinals on 19 April 2005, in such a way, that as from 28 February 2013, at 20:00 hours, the See of Rome, the See of Saint Peter, will be vacant and a Conclave to elect the new Supreme Pontiff will have to be convoked by those whose competence it is.
Dear Brothers, I thank you most sincerely for all the love and work with which you have supported me in my ministry and I ask pardon for all my defects. And now, let us entrust the Holy Church to the care of Our Supreme Pastor, Our Lord Jesus Christ, and implore his holy Mother Mary, so that she may assist the Cardinal Fathers with her maternal solicitude, in electing a new Supreme Pontiff. With regard to myself, I wish to also devotedly serve the Holy Church of God in the future through a life dedicated to prayer.
From the Vatican, 10 February 2013
BENEDICTUS PP XVI
In the past 1000 years, only four other popes have resigned.
Pope Benedict IX, in 1045 resigned to get married. He sold his position to his godfather.
Pope Gregory VI, in 1046 the godfather who had purchased the office from Pope Benedict IX left office. Benedict IX did not find marriage with the woman he had left for and changed his mind. Both Popes stayed in Rome. German Emperor Henry III, of the Holy Roman Empire, intervened by invading Rome to remove them both. Henry III treated Gregory VI as the rightful pope but the bishops urged Gregory VI to resign because he bribed his way into office.
Pope Celestine V, in 1294: Celestine V served five months in office and then declared that Popes had the right to resign. He promptly resigned.
Pope Gregory XII, in 1415: Gregory XII had held office for 10 years. But a division in the church left one pope in Rome and one in the French city of Avignon. Gregory XII resigned and a special council excommunicated the Avignon pope and declared a new leader.
The next morning following then end of the papal reign of Pope Benedict XVI a special mass will be held in the Sistine Chapel to begin the election process for the next pope. The College of Cardinals will convene later that afternoon. By secret ballot the cardinals will elect a new pope from among those cardinals under the age of 80. The balloting process is repeated until a favorite emerges and receives two-thirds plus one vote.
The ballots from each vote are burned. A special chemical added to the fire causes black smoke to rise from the chimney. When white smoke emerges, that is a signal that a new pope has been elected.