As the former Pope Benedict, now Pope Emeritus Benedict, enjoys his first hours of retirement with music and praying, the College of Cardinals will be getting down to business very soon.

Who is in this elite club that will decide the leader of the 1 billion Catholics in the world?

The College of Cardinals is currently comprised of 207 cardinals: 117 Cardinal electors who can vote in the election of the Pope and 90 cardinals who are over the age of 80. First in the order of the hierarchy are Cardinal-bishops. Currently six in number, these were originally the bishops of the dioceses of Rome.

Second and most numerous in the three orders of cardinals are the Cardinal-priests who are assigned the “titulos” (title) of the important churches of the Diocese of Rome.

Last in the order of cardinals are the Cardinal-deacons who were originally the seven deacons in the Papal Household and the seven deacons who supervised the Church’s works in the districts of Rome during the early Middle Ages, when church administration was effectively the government of Rome and provided for all of the city’s social services. Cardinal-deacons today are given title to one of these deaconries.

No earlier than 15 days and no later than 20 days, after Benedict’s resignation the cardinals must meet in conclave at the Sistine Chapel after taking a vow of secrecy. All cardinals are permitted to enter the conclave meeting, even cardinals who are not eligible to participate within the elected 120.