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, such as cars and motorcycles, where it helps drivers monitor engine performance and optimize gear shifts. Tachometers can be analog or digital, with analog versions featuring a dial and needle, while digital versions display the speed on a screen. They are essential for ensuring that engines operate within safe limits, preventing damage from excessive speeds. Many modern vehicles integrate tachometers into their dashboard displays for easy access.