The cardinals or so-called "princes of the church" are the pope's closest aides, representing a veritable think-tank of experienced churchmen.
There are essentially two types of cardinal - those who head Vatican departments and those who lead major dioceses around the world. They form the College of Cardinals and may be called together to assist the pope in dealing with complex or major questions.
However, the most important task of the College of Cardinals quite clearly is the election of a new pope. Only cardinals under the age of 80 may vote in a papal election, while the number of cardinal electors is nominally fixed at 120. Yesterday Pope Benedict named 23 new cardinals, with 18 of them under 80 and therefore entitled to vote.
These nominations bring the overall college number to 202, with 121 entitled to vote in a papal election.