We've all dealt with this problem: You have old computers you want to get rid of, and you'd like to give them to someone who could put them to use, but the data contained on the hard drives is a security issue. We all know that just deleting the files won't cut it, and neither will formatting the drive. There are various ways to address it: use an effective but time consuming "shredder" program that overwrites the disk multiple times with random characters, use a powerful magnet to erase the data, or yank the drive out and smash it to bits, and let the new owner buy a new drive.
Well, that was with traditional hard disks. Many of us are now moving to faster Solid State Drives (SSDs) and it has come to light that these are even more of a pain to erase than their predecessors. They don't use magnetic storage so forget the magnet, and degaussing doesn't destroy the electronics in the flash chips, either. Multiple overwriting is more complicated and takes longer because of the Firmware Translation Layer (FTL). It's almost impossible to security destroy a single file on an unencrypted disk. Ouch.
Read more about this problem here: