Chronograph vs. chronometer

What’s the difference between a chronograph and a chronometer?

Though they certainly sound similar, they are not the same. A chronograph is a stopwatch used for measuring and recording brief, precisely spaced intervals of time. Two “pushers” operate most chronographs: one to start and stop the chronograph’s second hand (usually) the top pusher) and the other to return that hand to the beginning position (usually the bottom pusher).

Chronometers, however, are watches that have undergone independent testing at a bureau in Switzerland called the Controle Officiel Suisse des Chronometres (COSC) to measure time precisely. If these watches pass the strict requirements of the COSC for accuracy, they are certified as chronometers.