The Free Software Foundation was started by Richard Stallman (creator
of the popular GNU Emacs editor). It is dedicated to eliminating
restrictions on copying, redistributing, and modifying software.
The word "free" in their name does not refer to price; it refers to
freedom. First, the freedom to copy a program and redistribute it to
your neighbors, so that they can use it as well as you. Second, the
freedom to change a program, so that you can control it instead of it
controlling you; for this, the source code must be made available to
you.
The Foundation works to provide these freedoms by developing free
compatible replacements for proprietary software. Specifically, they
are putting together a complete, integrated software system called
"GNU" that is upward-compatible with Unix. {As an aside, the editor
of the GNU project, emacs, contains a built-in LISP interpreter and a
large part of its functionality is written in LISP. The name GNU is
itself recursive (the mainstay of the LISP language); it stands for
"Gnu's Not Unix."}
When it is released, everyone will be permitted to copy it and
distribute it to others. In addition, it will be distributed with
source code, so you will be able to learn about operating systems by
reading it, to port it to your own machine, and to exchange the
changes with others.
For more information on the Free Software Foundation and the status of
the GNU Project, or for a list of the current tasks that still need to
be done, write to gnu@prep.ai.mit.edu.