I try to use consistent terminology throughout this document, so
that users of all free Unix-like systems, and even users of
non-Unix-like free software, can benefit. Unfortunately, there are
many handy ambiguous names and many awkward unambiguous names, so
just to be clear, here's a quick glossary of what each name means:
Unix is an operating system constructed at Bell Labs by
various researchers. A variety of operating systems, mostly
commercial, are based on this code and are also included in
the name Unix.
Un*x is an awkward word used to refer to every Unix-like
operating system. A Unixlike operating system provides
something similar to a POSIX programming interface as its
native API. GNU/Linux, FreeBSD, Solaris, AIX, and even
special-purpose systems like Lynx and QNX are all Un*x.
Linux is a Unixlike kernel and a small assortment of
peripheral software written by Linus Torvalds and
hundreds of other programmers. It forms the foundation of
the most widely used Un*x operating system.
The GNU (GNU's Not Unix) project is a longtime development
effort to produce an entirely free Unixlike operating system.
The GNU Project is in many ways the father of most modern free
A GNU/Linux operating system is a complete system
comprised of the Linux kernel, its peripheral programs, and
the GNU runtime environment of libraries, utilities, end-user
software, etc. Red Hat, Debian, Caldera, SuSE, TurboLinux,
and similar companies are all commercial vendors of complete