However when additional activity is performed by the computer, it can OVER_WRITE on the space occupied by the deleted file. When that happens, it is almost impossible to recover the data from the deleted file.
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If the hard drive is big enough, it will be a long time before anything is overwritten, as new data is written to free space where it left off from the previous write, methinks.
You are correct, but crooked democrats will use a simple App to over-write all deleted data with many passes of writing zeroes in every byte. I have that app which I use when I buy a cheap used laptop on line. It is ridiculously easy to use.