QUESTION: When I exercise the command to delete a file what really happens?

ANSWER: Drive space is not a single empty field waiting for data. In reality, drive space is divided up into small storage areas called clusters. When a file is stored, it is also broken up and alloted to fill free clusters across your hard drive. The FAT (file allocation table) only points to the first cluster used by the file - that first cluster points to the second cluster used by the file, the second cluster points to the third, and so on. When you delete a file, you’re not actually erasing the file’s data. Instead, you’re simply telling the operating system that the characters involved in that file are free for reuse. Thus, if you save a new file to the drive, that new file can overwrite some of those free clusters.

As long as you don’t overwrite any of the clusters used by the file, it is possible to undelete the file. It gets a little complicated, as you can see.

The only way to truly erase a file is to completely overwrite the data in each cluster used by the file. There are numerous tools that write patterns of data to each cluster, leaving the original file completely unrecoverable.

The Defense Department is reported to have a special program that will wipe out and obliterate existing files on a hard drive. There are probably other programs available. Try looking in GOOGLE for more information on this subject.