I’m not sure who did the copy and paste job from Wikipedia but you should have at least put it in as a note.

A disk editor is a computer program that allows its user to read, edit, and write raw data (at character or hexadecimal,     byte-levels) on disk drives (e.g., hard disks, USB flash disks or removable media such as a floppy disks); as such, they are sometimes called sector editors,since the read/write routines built into the electronics of most disk drives require to read/write data in chunks of sectors (usually 512 bytes). Many disk editors can also be used to edit the contents of a running computer’s memory or a disk image.