RPM is the acronym used for revolutions per minute. It measures the number of revolutions completed in one minute around a fixed axis, giving the speed of a mechanical component. It is commonly used to describe the performance of automobile engines.
In automobiles, RPM is a way to indicate how hard an engine is working. It is used in conjunction with torque to demonstrate not only the speed of an engine but how much power that engine can produce. For example, a truck engine and a sports car engine may have similar horsepower but different RPM measurements. Running an engine at a high RPM over time may cause damage to the engine and reduce its expected lifespan.