Chronometry

Chronometry (from Greek χρόνος chronos, "time" and μέτρον metron, "measure") or Horology (lit. 'the study of time'; related to Latin horologium; from Ancient Greek ὡρολόγιον (hōrológion) 'instrument for telling the hour'; from ὥρα (hṓra) 'hour, time', interfix -o-, and suffix -logy) is the science of the measurement of time, or timekeeping. Chronometry provides a standard of measurement for time, and therefore serves as a significant reference for many and various fields of science.

In current usage, horology refers mainly to the study of mechanical time-keeping devices, while chronometry more broadly includes biological behaviours seen in animals based in time (biochronometry), and the dating of geological materials (geochronometry).

The importance of the accuracy and reliability of measuring time provides a standardized unit for chronometric experiments for the modern world, and more specifically scientific research. Despite the coincidental identicality of worldwide units of time, time produces a measurement of change and is a variable in many experiments. Therefore, time is an essential part of many areas of science.

It should not be confused with chronology, the science of locating events in time, which often relies upon it.

Horology is commonly used specifically with reference to the mechanical instruments created to keep time: clocks, watches, clockwork, sundials, hourglasses, clepsydras, timers, time recorders, marine chronometers, and atomic clocks are all examples of instruments used to measure time. People interested in horology are called horologists. That term is used both by people who deal professionally with timekeeping apparatuses (watchmakers, clockmakers), as well as aficionados and scholars of horology. Horology and horologists have numerous organizations, both professional associations and more scholarly societies. The largest horological membership organisation globally is the NAWCC, the National Association of Watch and Clock Collectors, which is US based, but also has local chapters elsewhere.

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.

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.