User's Manual

58
Preamble
The licenses for most software are designed to take away
your freedom to share and change it. By contrast, the GNU
General Public License is intended to guarantee your freedom
to share and change free software--to make sure the software
is free for all its users. This General Public License applies to
most of the Free Software Foundation’s software and to any
other program whose authors commit to using it. (Some other
Free Software Foundation software is covered by the GNU
Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom,
not price. Our General Public Licenses are designed to make
sure that you have the freedom to distribute copies of free
software (and charge for this service if you wish), that you
receive source code or can get it if you want it, that you can
change the software or use pieces of it in new free programs;
and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the
rights. These restrictions translate to certain responsibilities
for you if you distribute copies of the software, or if you modify
it.
For example, if you distribute copies of such a program,
whether gratis or for a fee, you must give the recipients all
the rights that you have. You must make sure that they, too,
receive or can get the source code. And you must show them
these terms so they know their rights.