The remaining data on magnetic storage after deletion or erasure.

Data sanitization tools correct this problem by completely removing data from devices, making them suitable for disposal or reuse.

Data

Metadata

When you delete a file, the operating system removes the inode or the table entry corresponding to that file.

Data sanitization programs overwrite each disk location where the file's data was stored.

This obliterates the information that was stored on disk so that it can't be reconstructed.

You should always sanitize disks before disposing of them.

Modern data sanitization algorithms have improved substantially, to the point that they can successfully sanitize disks in a single pass.

Darik's Boot and Nuke (DBAN)

CBL Data Shredder

The format command with the write zero option