Why does deleted data stay on a HDD once written, waiting to be overwritten, as opposed to being removed when requesting deletion?
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Gonna give a bit of a hand-wavey explanation, but it gets to the point.
Data in computers works using something called pointers and addresses.
Addresses are values that describe WHERE the data is. Data is physically stored at that address.
Pointers are values that point to that an address and can access that data stored there.
Usually when something is deleted from a hard drive, the pointer is deleted, and that address of the disk is marked as “available for other things to be stored there”.
Sometimes, data is deleted, but it just happens that nothing has been saved over that part of the disk yet, so the data is still physically there and could theoretically be retrieved.
Overwriting the addresses so that they contain “nothing” would take just as long as writing the data to begin with, so instead computers just delete the pointer to the data.
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