damage

Damage is any change in a thing, often a physical object, that degrades it away from its initial state. It can broadly be defined as "changes introduced into a system that adversely affect its current or future performance". Damage "does not necessarily imply total loss of system functionality, but rather that the system is no longer operating in its optimal manner". Damage to physical objects is "the progressive physical process by which they break", and includes mechanical stress that weakens a structure, even if this is not visible. Efforts undertaken to prevent or ameliorate damage are often referred to as "damage control".

==Physical damage== thumb|right|Damage to an electric locomotive in Vraňany caused by a car crash thumb|right|Damage to a gas station in Texas caused by a hurricane thumb|right|Damage to cabbage leaves caused by insects thumb|right|Damage caused by military action in the Gulf War All physical damage begins on the atomic level, with the shifting or breaking of atomic bonds, and the rate at which damage to any physical thing occurs is therefore largely dependent on the elasticity of such bonds in the material being subjected to stress. Damage can occur where atomic bonds are not completely broken, but are shifted to create unstable pockets of concentration and diffusion of the material, which are more susceptible to later breakage. The effect of outside forces on a material depends on the relative elasticity or plasticity of the material; if a material tends towards elasticity, then changes to its consistency are reversible, and it can bounce back from potential damage. However, if the material tends towards plasticity, then such changes are permanent, and each such change increases the possibility of a crack or fault appearing in the material.