The method of simulated annealing (SA) draws its inspiration from the physical process of metallurgy and uses terminology that comes from that field. When a metal is heated to a sufficiently high temperature, its atoms undergo disordered movements of large amplitude. If one now cools the metal down progressively, the atoms reduce their movement and tend to stabilize around fixed positions in a regular crystal structure with minimal energy. In this state, in which internal structural constraints are minimized, ductility is improved and the metal becomes easier to work. This slow cooling process is called annealing by metallurgists and it is to be contrasted with the quenching process, which consists of a rapid cooling down of the metal or alloy.