Even though it is the first time since the fifteenth century that a pope has stepped down, it is unclear how long it has been — if ever — since a living pope willingly stepped down and left the seat vacated. In 1415, Pope Gregory XII stepped down because he was one of three men claiming to be the pope.
It is now up to the 115 Cardinal electors in the College of Cardinals to elect a new pope in a closed-door meeting that can sometimes take several days. During the election process smoke is released twice a day to signal whether or not a new pope has been chosen, as BBC News reports:
The only clue about what is going on inside the Sistine Chapel is the smoke that emerges twice a day from burning the ballot papers. Black signals failure. The traditional white smoke means a new pope has been chosen.
After the election of the new pope has been signalled by white smoke rising from the Sistine Chapel chimney, there will be a short delay before his identity is finally revealed to the world.
An article by The Guardian describes the six steps that will happen now that the pope has stepped down, a process that starts with the interregnum, the time where there is no pope and ends after the College of Cardinals elects and announces the new pope.
“I am no longer the pope,” said Benedict XVI, who has adopted the new title of emeritus pope or Roman pontifex emeritus. He also swore obedience to whoever his successor ends up being.
Below is a video of His Holiness addressing the College of Cardinals during his resignation.