Jitter is a very important performance parameter to consider when selecting timing devices. Knowing the jitter performance of timing devices enables designers to predict clock timing margins. Low jitter also prevents signal errors and globally improves the quality and reliability of the complete system. There are several ways to define jitter. There is no standard specification for defining jitter for timing devices and suppliers do not necessarily define jitter in the same way. It is important not to confuse jitter and wander; jitter is a measurement of higher frequency noise (up to one divided by the frequency). Wander is a low frequency variation measurement, less than 10 Hz phase variation.