inode

   A data structure holding information about files in a Unix
   file system.  There is an inode for each file and a file
   is uniquely identified by the file system on which it
   resides and its inode number on that system.  Each inode
   contains the following information: the device where the inode
   resides, locking information, mode and type of file, the
   number of links to the file, the owner's user and group ids,
   the number of bytes in the file, access and modification
   times, the time the inode itself was last modified and the
   addresses of the file's blocks on disk.  A Unix directory is
   an association between file leafnames and inode numbers.  A
   file's inode number can be found using the "-i" switch to ls.

   Unix manual page: fs(5).

   See also /usr/include/ufs/inode.h.