The pope's resignation sets in motion a complex sequence of events to elect the next leader of the Roman Catholic Church. The laws governing the selection are the same as those in force after a papal death. Here is the procedure:

:: The Vatican summons a conclave of cardinals that must begin 15 to 20 days after Benedict's February 28 resignation.

:: Cardinals eligible to vote - those under age 80 - are sequestered within Vatican City and take an oath of secrecy.

:: Any baptised Roman Catholic male is eligible for election as pope, but only cardinals have been selected since 1378.

:: Two ballots held each morning and two each afternoon in the Sistine Chapel. A two-thirds majority is required. Benedict in 2007 reverted back to this two-thirds majority rule, reversing a 1996 decision by Pope John Paul II, who had decreed that a simple majority could be invoked after about 12 days of inconclusive voting.

:: Ballots are burned after each round. Black smoke means no decision; white smoke signals that cardinals have chosen a pope and he has accepted. Bells also signal the election of a pope to help avoid possible confusion over colour of smoke coming from chimney of the Sistine Chapel.

:: The new pope is introduced from the loggia overlooking St. Peter's Square with the words "Habemus Papam!" (Latin for "We have a pope!") and he imparts his first blessing.