Unix is a very popular operating system that runs on almost every computer. It is highly portable, having been developed on a very portable language, C.
Another protocol and set of programs were developed to improve the services offered in networking (Nowitz and Kesk 1978). Originally, the protocol proposed was for file transfer-hence the nem uucp, an acronym for Unix to Unix Copy. However, many support programs were then written to take advantage of this capability. The mail program was rewritten so that it could take advantage of this file transfer procedure to transfer mail from one computer to another. Still, the "hardware used was that of a terminal port connected to another computer's terminal port. Security features were. weak, but controlled entirely by the superuser (a Unix term for system administrator).