The cardinalate developed gradually from the clergy attached to Rome's own parishes and suburban dioceses, whose senior members advised the Bishop of Rome on local church business well before the office carried its later international significance. The term cardinal derives from the Latin cardo, hinge, reflecting the sense of clergy hinged, or incardinated, to a specific Roman church. Popes began appointing cardinals from outside Italy in growing numbers from the thirteenth century onward, and by the modern era the College had become genuinely global, with Pope Francis and his predecessors deliberately elevating bishops from regions, including much of Africa, Asia and Oceania, that had rarely or never held a cardinal's hat.
A cardinal is created by the Pope alone, announced at a consistory, a formal gathering of the existing College, and receives the distinctive red biretta and cassock trim symbolizing a willingness to shed blood, martyrdom, in defense of the faith, language retained from the Church's early centuries even though modern cardinals rarely face that literal risk. Sede vacante, the period between a pope's death or resignation and the election of a successor, is governed by detailed provisions in canon law and papal constitutions specifying which of the College's ordinary powers continue and which are suspended, a body of procedural law developed particularly since the 1268 to 1271 conclave crisis at Viterbo.