In horology, a complication is any feature of a timepiece beyond the display of hours, minutes and seconds. A timepiece indicating only hours, minutes and seconds is known as a simple movement. Common complications include date or day-of-the-week indicators, alarms, chronographs (stopwatches), and automatic winding mechanisms. Complications may be found in any clock, but they are most notable in mechanical watches where the small size makes them difficult to design and assemble. A typical date-display chronograph may have up to 250 parts, while a particularly complex watch may have a thousand or more parts. Watches with several complications are referred to as grandes complications.
Three complications on a Gallet MultiChron Navigator (1943): a crown-controlled synchronizable second hand, a direction-finding 24-hour hand, and a 45-minute recording chronograph
Тhe Breguet No. 160 grand complication
Chronometry or horology is the science studying the measurement of time and timekeeping. Chronometry enables the establishment of standard measurements of time, which have applications in a broad range of social and scientific areas. Horology usually refers specifically the study of mechanical timekeeping devices, while chronometry is broader in scope, also including biological behaviours with respect to time (biochronometry), as well as the dating of geological material (geochronometry).
The hourglass is often used as a symbol representing the passage of time
Clocks; a watch-maker seated at his workbench
Chronos, the Greeks' personification of time
Ancient Egyptian sundial splitting daytime into 12 parts