When I delete a file on my computer, where does it go?
Sent to Recycle Bin or Trash
When you first delete a file on a computer, it is moved to the computer's Recycle Bin, Trash, or something similar depending on your operating system. When something is sent to the Recycle Bin or Trash, the icon changes to indicate it contains files and if needed allows you to recover a deleted file.
Later, when you empty the Recycle Bin or Trash, the icon changes back to an empty trash can and the files are deleted.
Do files in the Recycle Bin occupy disk space?
Yes. Because the files are not marked for delete they will still occupy disk space when stored in the Recycle Bin. Once it is emptied that disk space will be recovered.
Once the file is deleted
When a computer deletes a file or the Recycle Bin is emptied, it's removing the reference to the file on the hard drive. Once the file header, or reference, is removed, the computer can no longer see the file. The space the file took up is no longer reserved for that file, and any new file can be stored in that location.
What does this mean? The file is no longer readable by the computer. However, the file remains on the hard drive until another file or part of another file is saved to the same location.
Because the file is technically there, it may be able to be recovered using data recovery software, designed to rebuild the file header and allow the computer to see the file again. This software only works if no other file or data was saved over the top of the deleted file.
Why do computers not delete files?
It's much faster for a computer to remove the reference to a file than instructing the hard drive to overwrite the file with other data.
Making sure a file cannot be recovered
Running a low-level format or another utility that overwrites all deleted files with zeros or other garbage is the only method of making sure files cannot be recovered. A low-level format can also be called a zero fill, because of the writing of the zeroes to the hard drive. When the deleted file space is overwritten by zeroes or any other data, it is no longer able to be recovered.