Conclave (Osservatore Romano/Reuters/Robby Boey)

A conclave is the formal assembly of the College of Cardinals convened to elect the pope, the spiritual leader of the Catholic Church and the successor to Saint Peter. 

In the earliest centuries of Christianity, up until 1059, popes were chosen much like other bishops, by the clergy and faithful of Rome. To safeguard the independence of the Church and reduce outside political influence, reform measures gradually centralized the process. In 1059, the College of Cardinals was formally designated as the exclusive body of papal electors.

At the Second Council of Lyons in 1274, Pope Gregory X decreed that papal electors were to meet in strict seclusion cum clave (“with a key”), locked away until they reached a decision. This requirement gave rise to the term conclave.

Today, papal conclaves take place in the Sistine Chapel within the Apostolic Palace in Vatican City. Over the centuries, further refinements have shaped the electoral system. In 1970, Pope Paul VI established that only cardinals under the age of 80 may vote. The current procedural rules were issued by Pope John Paul II in Universi Dominici gregis (1996) and later modified by Pope Benedict XVI in 2007 and 2013.

To elect a new pope, a candidate must receive a two-thirds supermajority of the votes. This high threshold reflects the desire for broad consensus within the College of Cardinals in choosing the leader of the worldwide Catholic Church.

The image is that of an artist's impression of a photo of the 2013 Conclave.