Often mistaken for any watch which measures precise time (that would be a chronometer), a chronograph can be thought of more as an analog stop watch, a complication which is built into the movement of a timepiece. A basic chronograph has a start/stop button and a reset button. Most chronographs measure seconds utilizing a central seconds hand, while the time-only seconds hand is found in a sub dial. There are many types of chronograph, but a few of the most popular are Retour-En-Vol (Flyback), Rattrapante (split-seconds), and Monopoussoir (one-button).
A Retour-En-Vol chronograph, or Flyback, was originally designed for aviators who needed precise time measurement for navigation. The chronograph immediately resets to zero and begins counting time again when the second button is pressed. Flyback Chronographs are exceptions to the normal complication and are often found on specialized timepieces.
Rattrapante chronograph movements involve two second hands and are used to measure two periods of time that begin together but end differently, such as a race. Split-Second chronographs have a third pusher button and are immediately recognizable as they have two second hands on the face, albeit stacked on top of each other.
One-Button chronographs are historical to watchmaking and were the original iteration of the complication. The first two-button complications were introduced in the 1920s. The limitations of a monopoussoir chronograph can be found in the ability to start and stop the complication on a continued span of time. Depressing the single button for a second time resets the chronograph to zero.
Chronographs are iconic and have been used to measure time in races, aviation, even space travel.