The USN Journal, or Change Journal, is a feature of the Windows NT file system (NTFS) which maintains a record of changes made to the volume. It is not to be confused with the journal used for the NTFS file system journaling.
Uses
The USN Journal is used by the File History feature introduced in Windows 8 to determine which files have changed since the last backup so that only files that have changed are added to the history. The desktop search utility Everything monitors the journal to update its database of file names. ==References==