A tachometer is an instrument used to measure the rotational speed of an object, typically in revolutions per minute (RPM). It is commonly found in vehicles, where it helps drivers monitor the engine's speed to optimize performance and fuel efficiency. By providing real-time feedback, a tachometer can prevent engine over-revving, which can lead to damage. In addition to vehicles, tachometers are also used in various machinery and equipment, such as industrial motors and aircraft. They can be analog, featuring a dial and needle, or digital, displaying the information on a screen. This versatility makes tachometers essential for ensuring safe and efficient operation in many applications.