A chronograph is a type of watch which is a stopwatch combined with a standard watch. A basic chronograph has hour and minute hands on the main dial to tell the time, a small seconds hand to tell that the watch is running, and a seconds hand on the main dial (usually equipped with a sweeping movement for precision) accompanied by a minutes sub dial for the stopwatch. Another sub dial to measure the hours of the stopwatch may also be included on a chronograph. The stopwatch can be started, stopped, and reset to zero at any time by the user by operating pushers usually placed adjacent to the crown. More complex chronographs often use additional complications and can have multiple sub-dials to measure more aspects of the stopwatch such as fractions of a second as well as other helpful things such as the moon phase and the local 24-hour time. In addition, many modern chronographs include tachymeters on the bezels for rapid calculations of speed or distance. Louis Moinet invented the chronograph in 1816 for use in tracking astronomical objects. Chronographs soon found use in artillery fire in the mid to late 1800s, and over times became fixtures in fields as diverse as aircraft piloting, auto racing, diving and submarining.

Since the 1980s, the term chronograph has also been applied to all digital watches that incorporate a stopwatch function.

The term chronograph comes from the Greek χρονογράφος (khronográphos 'time recording'), from χρόνος (khrónos 'time') and γράφω (gráphō 'to write'). Early versions of the chronograph are the only ones that actually used any "writing": marking the dial with a small pen attached to the index so that the length of the pen mark would indicate how much time had elapsed. The first modern chronograph was invented by Louis Moinet in 1816, solely for working with astronomical equipment. It was Nicolas Mathieu Rieussec who developed the first marketed chronograph at the behest of King Louis XVIII in 1821. The King greatly enjoyed watching horse races, but wanted to know exactly how long each race lasted, so Rieussec was commissioned to invent a contraption that would do the job: as a result he developed the first ever commercialized chronograph. Rieussec was considered the inventor of the chronograph until the Louis Moinet pocket chronograph discovery in 2013 when history was rewritten. In addition to inventing the chronograph, Louis Moinet is also the father of High Frequency. In 1816, his Compteur de Tierces timepiece beat at a rhythm of 216,000 vibrations per hour (30 Hz). This frequency record stood for exactly one century, before eventually being broken in 1916, after which standard chronometer frequencies returned to present-day levels (generally 5–10 Hz, or 18,000 to 36,000 vibrations per hour). Still in perfect working order, the Compteur de Tierces is preserved at Ateliers Louis Moinet.

In 1913, Longines created the 13.33Z, one of the first chronograph movements ever developed for a wristwatch, featuring 18 jewels, a diameter of 29 mm and height of 6 mm, and a beat rate of 18,000 vph. It utilized a crown that was used both for winding the watch and serving as a pusher for the chronograph.

In 1915, Gaston Breitling produced the first chronograph with a central seconds hand and a 30-minute counter. Later, in 1923, Gaston Breitling introduced the first chronograph with a separate pusher at 2 o'clock. In 1934 Willy Breitling further developed the concept of the chronograph with the addition of the second pusher at 4 o'clock. Since then the 3-pusher chronograph design has been adopted by the entire industry.

In 1844 Adolphe Nicole's updated version of the chronograph was the first to include a re-setting feature which now allowed successive measurements, unlike the constantly moving needle in the original chronograph.

In the early part of the 20th century, many chronographs were sold with fixed bezels marked in order to function as a tachymeter. In 1958 the watch company Heuer introduced a model with a rotating bezel tachymeter for more complex calculations.

Chronographs were very popular with aviators as they allowed them to make rapid calculations and conduct precise timing. The demand for chronographs grew along with the aviation industry in the early part of the 20th century. As the US exploration of outer space initially involved only test pilots, by order of President Dwight D. Eisenhower, chronographs were on the wrists of many early astronauts. Chronograph usage followed a similar trajectory for many fields that involve very precise and/or repeated timing around increasingly more complicated high performance machinery, automobile racing and naval submarine navigation being two examples. As different uses for the chronograph were discovered, the industry responded with different models introducing such features as the flyback (where the second hand could be rapidly reset to zero), minute and hour timers, rattrapante (or multiple second hands one of which can be stopped and started independently) and waterproof models for divers and swimmers.