RPM stands for “revolutions per minute,” a measurement of how many times something spins completely around in sixty seconds. If a ceiling fan makes 100 complete rotations in one minute, it's spinning at 100 rpm.

You'll see rpm used most often with engines and motors. A car engine might idle at 800 rpm, meaning its internal parts complete 800 full rotations every minute. When you press the accelerator, the rpm increases: the engine spins faster to give the car more power. Race car engines can reach 15,000 rpm or higher, spinning so fast the parts become a blur.

The concept applies to anything that rotates. A vinyl record player spins at 33⅓ rpm (for albums) or 45 rpm (for singles). A hard drive in a computer might spin at 7,200 rpm to quickly read and write data. Even a fidget spinner has an rpm, though most people don't measure it.

Engineers and mechanics watch rpm carefully because spinning too fast can damage machinery, while spinning too slowly might not generate enough power. The tachometer on a car dashboard shows the engine's current rpm, helping drivers know when to shift gears. Understanding rpm helps you appreciate how rotational speed affects everything from the music you hear to the car you ride in.