If you’re about to sell or give away a computer, it’s important to ensure that all of your personal data is erased first. This is a pretty simple task when it comes to traditional spinning hard drives, and there are plenty of tools to make sure the drive is completely and securely wiped. Solid State Drives, however, are a different story. SSDs use something called “wear leveling,” which ensures that no one cell gets written to too many times. This is to keep the drive from wearing out, but it also means that it isn’t possible to write over (or erase) every part of the drive.