The ability of a system to exist in two steady states. Bistability is a necessary condition for oscillations to occur in chemical reactions. The two steady states of a bistable system are not states of thermodynamic equilibrium, as they are associated with conditions far from equilibrium. Chemical reactions involving bistability jump suddenly from one state to the other state when a certain concentration of one of the participants in the reaction is reached. The effect is analogous to the phenomenon of supercooling, i.e. the cooling of a liquid below its freezing point without freezing. See also oscillating reaction.