The cancellation of the effect of one process by another process that operates at the same time with the opposite effect. An example of detailed balance is provided by a chemical reaction between two molecular species A and B, which results in the formation of the molecular species C and D. Detailed balance for this chemical reaction occurs if the rate at which the reaction A+B → C+D occurs is equal to the rate at which the reaction C+D → A+B occurs. The equilibrium state in thermodynamics is characterized by detailed balance. When there is detailed balance in a system, the self-organization far from equilibrium associated with nonequilibrium statistical mechanics cannot occur.