Why does deleted data stay on a HDD once written, waiting to be overwritten, as opposed to being removed when requesting deletion?

Question

Why does deleted data stay on a HDD once written, waiting to be overwritten, as opposed to being removed when requesting deletion?

In: 22

Answer 1

Imagine laying out dominoes to represent information. Literally those *black little wooden rectangles*.

Your disk has a Table of Content, which tells it: “*hey, dominoes number 35 to 79 contain THIS type of information*”.

When you “*delete*” the file, you tell the TOC: “*Hey, forget about dominoes 35 to 79*”.

So it shows them as being available for storing new information. But these dominoes are still in place. If someone looked at them, they might be able to make up the information.

This is how data recovery works. Even if your TOC is lost, it’s still possible to try to make sense of the information. But it’s probably like a million piece puzzle.

When you *overwrite* your disk, you actually mix the dominoes up and the information is no longer there to be seen.