Did you know that files are not actually removed from your hard drive when you delete them in Windows (I don’t know about other operating systems, but I think they’re the same), even if you empty the Recycle Bin?
The files and folders you “delete” are actually still on the drive, except they’re hidden. This was implemented into the file system to allow for a much faster deletion speed (it takes quite a while to completely delete a file, about 5 minutes per GB on newer hard drives) and to give the user a possibility to get his data back in case of an accidental deletion or quick formatting (full formatting removes all data, but can take up to a few hours to complete).
So, if you have any sensitive data and think that you can delete it anytime if the circumstances require it, you are in for a big surprise. Using a data restoration utility like Norton Save & Restore or R-Studio, anyone can undelete your files and open them, exposing all your secrets.
Let’s say you really don’t want that to happen. How should you proceed?
One way to do it would be writing unimportant data like music and movies over the deleted, now hidden files. This would physically remove them to make space for the new ones. But you wouldn’t know where exactly were they written on the surface of the disk (they could be at the beginning, middle, end, or scattered all around if your drive was heavily fragmented), so you’ll have to fill all of the free space with unimportant files to be sure they’re really gone.