We’ve all failed to eject a USB drive before unplugging it, prompting warnings–but not absolute truths–about lost data. Knowing the mechanics of three common storage devices could save you precious time, 1s, and 0s.

Traditional hard drives can store terabytes of data on spinning, magnetized disks. Unplugging a hard drive, however, can cause data-reading components to suddenly crash into them. Damage is rare but severe, ranging from permanent errors to a dead drive. Better safe than sorry. Always click Eject.

Solid-state drives, or SSDs, lack the moving parts and whirring sounds of hard drives. They’re more yank-friendly–with two caveats: SSDs can’t be transferring data or running TRIM, a command that “trims” away deleted data to boost speed. Sudden removal can fry tiny components, so eject SSDs, too.

As for pinkie-size flash drives? Yank them at your leisure, unless, that is, you’ve turned on write-cache mode. This process offloads files to computer memory to increase transfer speeds. Unplugging the drive before it’s done copying data can cause it to fail. Fortunately, most devices don’t enable write-cache by default, and many computers disable it the moment a drive is plugged in.