It is our common household experience that when the voltage drop across a fuse exceeds a limit, the fuse burns out. A fuse is nothing but a conductor that conducts uniform current under an applied voltage up to a certain limit beyond it burns out and becomes non-conducting. This is called fuse failure. Similarly, in a dielectric breakdown, a dielectric starts to conduct electricity when the voltage drop across it attains certain threshold value. The above two phenomena are examples of breakdown process that is described broadly as the failure of a physical attribute when the perturbing force driving it goes beyond a limiting value. The most common example of the process is the breaking of a material at a high stress beyond its strength.