A chronograph is a type of watch that combines standard timekeeping with a stopwatch function. It typically features additional dials or sub-dials that measure elapsed time, allowing users to track events with precision. Chronographs are popular among athletes and professionals who need to time activities accurately. These watches often have buttons on the side to start, stop, and reset the stopwatch feature. Many chronographs also include a tachymeter scale, which can be used to calculate speed based on time and distance. Brands like Rolex and Tag Heuer are well-known for their high-quality chronograph models.