The College of Cardinals
The College of Cardinals is the body encompassing all cardinals of the Catholic Church. The College of Cardinal's function is to advise the Pope concerning church matters when they are summoned to an ecclesiastical council called the ordinary consistory. The College of Cardinals also convenes upon the death or resignation of a pope as a papal conclave. The Conclave elects a new pope. The college only has ruling power during the period of papal vacancy. However during that time its powers are extremely limited by the terms of the current law which is stated in the Fundamental Law of the Vatican City and the Apostolic Constitution Universi Dominici Gregis.
The cardinals were the clergy of the city of Rome who served the Bishop of Rome as the Pope and had clerical duties in Rome's parishes. The College of Cardinals was formed due to a power struggle that started with the crowning of Henry IV as King of Germany and the Holy Roman Emperor after the unexpected death of Henry III in 1056. Henry the IV was only six years old at the time. The college started meeting regularly from the 12th century.
The Dean of the College of Cardinals and the Sub-Dean are the president and vice-president of the college. Both of them are elected by and from the cardinals holding suburbicarian dioceses. However, the election requires papal confirmation. The dean has no authority over the cardinals.
Among the most important roles of the College of Cardinals is the election of a new pope. When a pope dies or resigns the cardinals converge for the papal conclave. They abide by the rules stipulated in the apostolic Constitution concerning the election of the pope until a new pope is elected. A simple two-third majority is required to announce the leading candidate as the new pope.
The size of the College of Cardinals has been limited by the popes, ecumenical councils and even the College itself. Between 1099 and 1986, the number of cardinals appointed was approximately 2900 in total. Between 1300 and 1600 there was a struggle between the current cardinals and the reigning popes concerning the number of Cardinals in the College. One of the best ways for the pope to make himself more powerful was to add more cardinals who supported him. Several popes used the tactic of increasing the number of cardinals in the College of Cardinals so as to be assured of support during their reign. The other cardinals opposed this tactic as they saw it as a way of weakening their power.
There are three categories in the College of Cardinals. The highest rank is Cardinal Bishop, then Cardinal Priest, and finally Cardinal Deacon. Inside each category the status of a cardinal is determined by his seniority. Some of the cardinals also serve in different capacities such as presidents of various authorities, prefects of different bodies, etc. For example; the Secretary of the Vatican State, the prefects of the Congregations of the Roman Curia, the Camerlengo of the Holy Roman Church, the Vicar General of Rome, and the Patriarchs of Venice and Lisbon, are normally Cardinals.