post of pope.
There are no official candidates, no open campaigning and no clear front runner for the job. Cardinals tipped as favourites by Vatican watchers include Brazil's Odilo Scherer, Canadian Marc Ouellet, Ghanaian Peter Turkson, Italy's Angelo Scola and Timothy Dolan of the United States.
Benedict, a bookish man who did not seek the papacy and did not enjoy the global glare it brought, proved to be an energetic teacher of Catholic doctrine but a poor manager of the Curia, the Vatican bureaucracy that became mired in scandal during his reign.
He leaves his successor a top secret report on rivalries and scandals within the Curia, prompted by leaks of internal files last year that documented the problems hidden behind the Vatican's thick walls and the Church's traditional secrecy.
After about two months at Castel Gandolfo, Benedict plans to move into a refurbished convent in the Vatican Gardens, where he will live out his life in prayer and study, "hidden to the world", as he put it.
Having both a retired and a serving pope at the same time proved such a novelty that the Vatican took nearly two weeks to decide his title and form of clerical dress.
He will be known as the "pope emeritus," wear a simple white cassock rather than his white papal clothes and retire his famous red "shoes of the fisherman," a symbol of the blood of the early Christian martyrs, for more pedestrian brown ones.