dd is a utility distributed with the GNU Coreutils package and which “copies a file (from standard input to standard output, by default) with a changeable I/O block size, while optionally performing conversions on it.” The utility has been the cornerstone for forensic imaging and also, if misused, can quickly destroy a disk.  As such, dd is theorized to have two means, Disk Duplicator or Disk Destroyer.

Two key forensic imaging utilities are branched from the dd code, namely dcfldd and dc3dd.