Source : Free On-Line Dictionary of Computing

back-end
     
         Any software performing either the final stage
        in a process, or a task not apparent to the user.  A common
        usage is in a {compiler}.  A compiler's back-end generates
        {machine language} and performs optimisations specific to the
        machine's {architecture}.
     
        The term can also be used in the context of {network}
        applications.  E.g. "The back-end of the system handles
        {socket} protocols".
     
        Contrast {front end}.
     
        (1996-04-09)