When you a delete a file, it isn’t really erased – it continues existing on your hard drive, even after you empty it from the Recycle Bin. This allows you (and other people) to recover files you’ve deleted.
If you’re not careful, this will also allow other people to recover your confidential files, even if you think you’ve deleted them. This is a particularly important concern when you’re disposing of a computer or hard drive.
What Happens When You Delete a File
Windows (and other operating systems) keep track of where files are on a hard drive through “pointers.” Each file and folder on your hard disk has a pointer that tells Windows where the file’s data begins and ends.
When you delete a file, Windows removes the pointer and marks the sectors containing the file’s data as available. From the file system’s point of view, the file is no longer present on your hard drive and the sectors containing its data are considered free space.
However, until Windows actually writes new data over the sectors containing the contents of the file, the file is still recoverable. A file recovery program can scan a hard drive for these deleted files and restore them. If the file has been partially overwritten, the file recovery program can only recover part of the data.
Note that this doesn’t apply to solid-state drives (SSDs) – see below for why.
More
Actually the newest generation of harddrives will NEVER forget which files you did have on your harddrive.
Maxtor, Seagate and Western Digital have specific tools available for law enforcement that can recover files up to over 100 reinstall events and partition wipes.
Which means that lets say for example: Some sick dude who likes to have VERY wrong pictures and VERY wrong video's on his computer, if he uses a harddrive cleaner (lowlevel) or a fresh install to get rid of evidence he can do that over a 100 times, and by doing so totally remove any trace of his sick online habits.
However forensic computer technicians can recover those files and the sick mofo is still going to jail for hopefully at least 100 years.
Personally i am not sure where the HDD would store these files, but i have been told that the latest generation of harddrives actually have a dual drive where very small file details are being stored, and a user cannot remove them regardless what he does.
Would that mean that every file is being stored? No but based upon specific file details the computer is capable of indexing the file and predict if the file meets "harmfull" or "illegal" criteria and thus is being flagged for long time storage.
Also MS indexing service is indexing files on your PC and sends data strings to MS which also has the ability to keep certain files in micro storage.
And this is one of many ways why a internet asshole always gets caught.
Cheers
