An instrument commonly used to measure speed is a speedometer. Speedometers are typically found in vehicles and provide real-time feedback to the driver regarding how fast the vehicle is traveling. They function by measuring the rotation of the wheels and translating this rotation into a speed reading, usually displayed in miles per hour (mph) or kilometers per hour (km/h). In addition to conventional vehicles, speedometers are also used in various forms of transportation, including bicycles and boats. Accurate speed measurement is crucial for safety, performance, and compliance with traffic regulations on the roads.