When you create a hard link, you are adding information to the original file's NTFS directory entry. So, the operating system itself is responsible for maintaining the link, even if you move or rename the original file. Instead, it's simply a pointer to the original file. If you add a single hard link to a file, you will have a total of two hard links associated with that file.
Hard links do have a couple of disadvantages.
Unlike shortcuts, hard links must reside on a NTFS volume. And since the hard links are really directory entries, both the original file and the links must reside on the same NTFS volume. If you move the original file to another drive, then move it back, you will have broken all the links to the file. From a programmer's viewpoint, although it's easy to tell how many links a particular file has, it is very tedious to discover the location of the links themselves. Sometimes you need to have multiple references to a single file in multiple directories.