A pause in a microprocessor's clock cycles that allows for differences in speed between one component and others in a computer, such as input/output devices or RAM. Wait states are common in systems where the microprocessor has a much higher clock speed than other components. During a wait state, the microprocessor idles for one or more cycles while data comes in from RAM or other components. Although unnoticeable to users, this idling can affect a system's performance because it involves the microprocessor's clock speed; if clock speed is reduced, system performance will slow. Wait states also are not uncommon between buses and expansion cards, where the expansion cards run slower than their buses.