A mechanical marvel, that is powered by a mighty mainspring, which sends power through, typically, 4 gears and their pinions to a finely tuned balance. All that only to tell you the time of day.
Many watches also possess extra functions (or complications) such as:
-stopwatches (chronographs)
-showing the current date
-the ever beloved automatic winding of the mainspring
Though not as needed in the current times, they still are beautiful constructs, used to show status, or just to look nice.
(also: digital watches)
(also: time)