Conclave
The conclave is an assembly of all the Cardinals of the Catholic Church, younger than age 80, which privately selects the next Pope in the event of a vacancy.
The term "conclave" can also be used to refer to any private assembly, although its primary connotation is the Papal conclave.
Procedure
"Conclaves must begin within 15 to 20 days after a pope dies or resigns. Upon the pope's death, the dean of the College of Cardinals calls the cardinal electors to the Vatican. There are currently 135 of them. To join the conclave, cardinals must be under 80 years old. During the conclave, the cardinals live in the Domus Sanctae Marthae, a [three-star] hotel-like facility next to St. Peter's Basilica."[1]
Secrecy and seclusion govern a conclave, based on an oath. Excommunication occurs for any breach.
White smoke appears from a chimney once a winner is selected. Since 1900 all the conclaves have been completed in less than four days.