Chronometry (from Greek χρόνος chronos, "time" and μέτρον metron, "measure") is the science of the measurement of time, or timekeeping.[1] And with the measurement, Chronometry employs the standardisation of time as well, serving as a significant reference for many and various fields of science.

The importance of the accurate and reliable measurement of time in addition to providing a standardized unit for chronometric experiments to the modern world and more specifically scientific research is immense. Despite the coincidental identicality of worldwide units of time, time produces a measure of change, and is a variable in many experiments, so time – and its standardization - is an essential part of many areas of science.

It should not to be confused with chronology, the science of locating events in time, which often relies upon it. Also, of similarity to Chronometry is Horology, the study of time, however it is commonly used specifically with reference to the mechanical instruments created to keep time, with examples such as stopwatches, clocks, and hourglasses. Chronometry is utilised in many areas, and its fields are often derived from aspects of other areas in science, for example geochronometry, combining geology and chronometry.

Early records of time keeping are thought to have originated in the paleolithic era, with etchings to mark the passing of moons in order to measure the year. And then progressed to written versions of calendars, before mechanisms and devices made to track time were invented. Today, the highest level of precision in timekeeping comes with atomic clocks, which are used for the international standard of the second.[2][3]