On bread and water, and let the cardinals get wet: the historical keys to the conclaves

The white smoke that ends up spreading over the Piazza Sant Pere in the Vatican is the result of a meticulous process that culminates with the"Habemus papam". A smoke that, after the death of Pope Francis, will give way to the announcement of the next pontiff once the conclave has found a candidate. This is a procedure with an eight-century tradition after processes that in some cases were chaotic. When did it emerge and why? Is it true that they were left to their own devices until a pope was elected? How have conclaves evolved?