Tach, short for 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 engine performance and avoid over-revving. In addition to automotive applications, tachometers are also used in various machinery and equipment to ensure optimal operation. They can be analog or digital, providing real-time feedback on speed, which is crucial for maintaining efficiency and safety in operations involving rotating parts, such as in engines and industrial machines.