http://y7yea4pmqqtznb33qiugvysyn2bob5v62e4pvoadoibrwkq3tsddjeyd.onion/zh-hans/module/how-delete-your-data-securely-windows
As a side effect, sometimes instead of erasing and writing the block a file was originally stored on, the drive will instead leave that block alone, mark it as invalid, and then write the modified file to a different block. This is kind of like leaving the page in the book unchanged, writing the modified file on a different page, and then just updating the book’s table of contents to point to the new page.