A hard link is a directory entry for a file, and it serves as a file system-level shortcut to the file. Unlike an application-level link, any updates to the file contents are seen by all applications that access the file using a hard link. Unlike a symbolic link, a hard link created on one NTFS volume cannot point to a file in a different NTFS volume.
When you create a hard link for a file on an NTFS volume, NTFS adds hard link information and a reference count to the file’s directory entry at the NTFS level. Creating the hard link does not create a duplicate original file or duplicate file-based reference (the application-level link).
While the physical file remains intact in its original location, you can access the same content by two or more names. Because the file system is responsible for managing the various path names to a single physical content, using a hard link can conserve system resources and storage system disk space compared to performing a standard file copy operation.