English: The term relaxation denotes the return of a system to equilibrium, and in chemical kinetics, it is used to indicate the re-adjusting that a reaction has to make in response to a sudden (normally) disturbance of an equilibrium. Sudden changes could include a sudden temperature jump, induced, for example by discharging a capacitor through a sample made conducting by addition of ions, or, by laser or microwave discharge, or a sudden pressure jump (in cases where the equilibrium is effected by pressure).