A hard link associates a name with the underlying file in the file system (inode). Meaning that every file must have at least one hard link to it and creating additional links makes the contents of that file accessible via additional paths and once the user deletes all of the hard links, the operating system frees the disk space that the file once occupied essentially deleting the file. 

By contrast, a symbolic link to a file is not a direct link to the data itself, but rather a reference to a hard link or another symbolic link via its path.
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