Every self-respecting file system identifies files and directories using numbered data structures. In most modern file systems, those data structures are known as inodes, and their numbers are inode numbers, sometimes shortened to inodes. The term is thought to be a contraction of index node, which certainly makes sense, but is lost in the mists of time. In any file system, for example an individual APFS volume, the inode numbers uniquely identify each inode, and each object within that file sys...