The working principle of simulated annealing is borrowed from metallurgy: a piece of metal is heated and then the metal is left to cool slowly. The slow and regular cooling of the metal allows the atoms to slide progressively toward their most stable, minimal energy, positions. Rapid cooling would have "frozen" them in whatever position they happened to be at that time. The resulting structure of the metal is stronger and more stable. By simulating the process of annealing inside a computer program, we are able to find answers to difficult and very complex problems. Instead of minimizing the energy of a block of metal or maximizing its strength, the program minimizes or maximizes some objective relevant to the problem at hand.