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-revision 1.132 by ineiev,
Fri Mar 14 04:04:58 2014 UTC
+revision 1.168 by ineiev,
Tue Jul 30 10:09:02 2019 UTC
 Line 1
  <!--#include virtual="/server/header.html" -->
- <!-- Parent-Version: 1.76 -->
+ <!-- Parent-Version: 1.86 -->
  <title>What is free software?
  - GNU Project - Free Software Foundation</title>
+ <style type="text/css" media="print,screen"><!--
+ .note { margin-left: 6%; margin-right: 6%; }
+ @media (min-width: 48em) {
+    .note { margin-top: .8em; }
+ }
+ --></style>
  <meta http-equiv="Keywords" content="GNU, FSF, Free Software Foundation, Linux, Emacs, GCC, Unix, Free Software, Operating System, GNU Kernel, HURD, GNU HURD, Hurd" />
  <meta http-equiv="Description" content="Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use." />
-Line 11
+Line 16
  <h2>What is free software?</h2>
+ <div class="article">
  <h3>The Free Software Definition</h3>
- <blockquote>
+ <blockquote class="note" id="fsf-licensing"><p style="font-size: 80%">
+ Have a question about free software licensing not answered here?
+ See our other <a href="http://www.fsf.org/licensing">licensing resources</a>,
+ and if necessary contact the FSF Compliance Lab
+ at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p>
+ </blockquote>
+ <div class="comment">
  <p>
  The free software definition presents the criteria for whether a
  particular software program qualifies as free software.  From time to
-Line 22 
 about subtle issues.  See the <a href="#
+Line 35 
 about subtle issues.  See the <a href="#
  below for a list of changes that affect the definition of free
  software.
  </p>
- </blockquote>
+ <p>
+ &ldquo;Open source&rdquo; is something different: it has a very
+ different philosophy based on different values.  Its practical
+ definition is different too, but nearly all open source programs are
+ in fact free.  We explain the
+ difference in <a href="/philosophy/open-source-misses-the-point.html">
+ Why &ldquo;Open Source&rdquo; misses the point of Free Software</a>.
+ </p>
+ </div>
  <p>
  &ldquo;Free software&rdquo; means software that respects users'
-Line 31 
 freedom to run, copy, distribute, study,
+Line 53 
 freedom to run, copy, distribute, study,
  software</b>.  Thus, &ldquo;free software&rdquo; is a matter of
  liberty, not price.  To understand the concept, you should think of
  &ldquo;free&rdquo; as in &ldquo;free speech,&rdquo; not as in
- &ldquo;free beer&rdquo;.
+ &ldquo;free beer&rdquo;.  We sometimes call it &ldquo;libre
+ software,&rdquo; borrowing the French or Spanish word for
+ &ldquo;free&rdquo; as in freedom, to show we do not mean the software
+ is gratis.
  </p>
  <p>
-Line 45 
 program <a href="/philosophy/free-softwa
+Line 70 
 program <a href="/philosophy/free-softwa
  an instrument of unjust power</a>.
  </p>
+ <h4> The four essential freedoms</h4>
  <p>
  A program is free software if the program's users have the
- four essential freedoms:
+ four essential freedoms: <a href="#f1">[1]</a>
  </p>
- <ul>
+ <ul class="important">
-   <li>The freedom to run the program, for any purpose (freedom 0).</li>
+   <li>The freedom to run the program as you wish,
+       for any purpose (freedom 0).</li>
    <li>The freedom to study how the program works, and change it so it
        does your computing as you wish (freedom 1). Access to the source
        code is a precondition for this.
    </li>
-   <li>The freedom to redistribute copies so you can help your neighbor
+   <li>The freedom to redistribute copies so you can help others
        (freedom 2).
    </li>
    <li>The freedom to distribute copies of your modified versions
-Line 72 
 freedoms.  Otherwise, it is nonfree.  Wh
+Line 100 
 freedoms.  Otherwise, it is nonfree.  Wh
  nonfree distribution schemes in terms of how far they fall short of
  being free, we consider them all equally unethical.</p>
- <p>The rest of this page clarifies certain points about what makes
+ <p>In any given scenario, these freedoms must apply to whatever code
- specific freedoms adequate or not.</p>
+ we plan to make use of, or lead others to make use of.  For instance,
+ consider a program A which automatically launches a program B to
+ handle some cases.  If we plan to distribute A as it stands, that
+ implies users will need B, so we need to judge whether both A and B
+ are free.  However, if we plan to modify A so that it doesn't use B,
+ only A needs to be free; B is not pertinent to that plan.</p>
- <p>Freedom to distribute (freedoms 2 and 3) means you are free to
+ <p>
- redistribute copies, either with or without modifications, either
+ &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free
- gratis or charging a fee for distribution, to
+ program must be available for commercial use, commercial development,
- <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these
+ and commercial distribution.  Commercial development of free software
- things means (among other things) that you do not have to ask or pay
+ is no longer unusual; such free commercial software is very important.
- for permission to do so.
+ You may have paid money to get copies of free software, or you may have
+ obtained copies at no charge.  But regardless of how you got your copies,
+ you always have the freedom to copy and change the software, even to
+ <a href="/philosophy/selling.html">sell copies</a>.
  </p>
  <p>
- You should also have the freedom to make modifications and use them
+ A free program must offer the four freedoms to any user that obtains a
- privately in your own work or play, without even mentioning that they
+ copy of the software, provided the user has complied thus far with the
- exist.  If you do publish your changes, you should not be required to
+ conditions of the free license covering the software.  Putting some of
- notify anyone in particular, or in any particular way.
+ the freedoms off limits to some users, or requiring that users pay, in
+ money or in kind, to exercise them, is tantamount to not granting the
+ freedoms in question, and thus renders the program nonfree.
  </p>
+ <h3>Clarifying the line at various points</h3>
+ <p>In the rest of this article we explain more precisely how far the
+ various freedoms need to extend, on various issues, in order for a
+ program to be free.</p>
+ <h4>The freedom to run the program as you wish</h4>
  <p>
  The freedom to run the program means the freedom for any kind of person
  or organization to use it on any kind of computer system, for any kind of
-Line 102 
 for her purposes, but you are not entitl
+Line 148 
 for her purposes, but you are not entitl
  </p>
  <p>
- The freedom to redistribute copies must include binary or executable
+ The freedom to run the program as you wish means that you are not
- forms of the program, as well as source code, for both modified and
+ forbidden or stopped from making it run.  This has nothing to do with what
- unmodified versions.  (Distributing programs in runnable form is necessary
+ functionality the program has, whether it is technically capable of
- for conveniently installable free operating systems.)  It is OK if there
+ functioning in any given environment, or whether it is useful for any
- is no way to produce a binary or executable form for a certain program
+ particular computing activity.</p>
- (since some languages don't support that feature), but you must have the
- freedom to redistribute such forms should you find or develop a way to
+ <p>For example, if the code arbitrarily rejects certain meaningful
- make them.
+ inputs&mdash;or even fails unconditionally&mdash;that may make the
- </p>
+ program less useful, perhaps even totally useless, but it does not
+ deny users the freedom to run the program, so it does not conflict
+ with freedom 0.  If the program is free, the users can overcome the
+ loss of usefulness, because freedoms 1 and 3 permit users and
+ communities to make and distribute modified versions without the
+ arbitrary nuisance code.</p>
+ <h4>The freedom to study the source code and make changes</h4>
  <p>
  In order for freedoms 1 and 3 (the freedom to make changes and the
- freedom to publish the changed versions) to be meaningful, you must have
+ freedom to publish the changed versions) to be meaningful, you need to have
  access to the source code of the program.  Therefore, accessibility of
  source code is a necessary condition for free software.  Obfuscated
  &ldquo;source code&rdquo; is not real source code and does not count
-Line 127 
 the original.  If the program is deliver
+Line 180 
 the original.  If the program is deliver
  run someone else's modified versions but refuse to run yours &mdash; a
  practice known as &ldquo;tivoization&rdquo; or &ldquo;lockdown&rdquo;,
  or (in its practitioners' perverse terminology) as &ldquo;secure
- boot&rdquo; &mdash; freedom 1 becomes a theoretical fiction rather
+ boot&rdquo; &mdash; freedom 1 becomes an empty pretense rather than a
- than a practical freedom.  This is not sufficient.  In other words,
+ practical reality.  These binaries are not free
- these binaries are not free software even if the source code they are
+ software even if the source code they are compiled from is free.
- compiled from is free.
  </p>
  <p>
-Line 142 
 license is too restrictive to qualify as
+Line 194 
 license is too restrictive to qualify as
  </p>
  <p>
+ Whether a change constitutes an improvement is a subjective matter.
+ If your right to modify a program is limited, in substance, to changes that
+ someone else considers an improvement, that program is not free.
+ </p>
+ <h4>The freedom to redistribute if you wish: basic requirements</h4>
+ <p>Freedom to distribute (freedoms 2 and 3) means you are free to
+ redistribute copies, either with or without modifications, either
+ gratis or charging a fee for distribution, to
+ <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these
+ things means (among other things) that you do not have to ask or pay
+ for permission to do so.
+ </p>
+ <p>
+ You should also have the freedom to make modifications and use them
+ privately in your own work or play, without even mentioning that they
+ exist.  If you do publish your changes, you should not be required to
+ notify anyone in particular, or in any particular way.
+ </p>
+ <p>
  Freedom 3 includes the freedom to release your modified versions
  as free software.  A free license may also permit other ways of
  releasing them; in other words, it does not have to be
-Line 151 
 as a free license.
+Line 226 
 as a free license.
  </p>
  <p>
- In order for these freedoms to be real, they must be permanent and
+ The freedom to redistribute copies must include binary or executable
- irrevocable as long as you do nothing wrong; if the developer of the
+ forms of the program, as well as source code, for both modified and
- software has the power to revoke the license, or retroactively add
+ unmodified versions.  (Distributing programs in runnable form is necessary
- restrictions to its terms, without your doing anything wrong to give
+ for conveniently installable free operating systems.)  It is OK if there
- cause, the software is not free.
+ is no way to produce a binary or executable form for a certain program
+ (since some languages don't support that feature), but you must have the
+ freedom to redistribute such forms should you find or develop a way to
+ make them.
  </p>
+ <h4>Copyleft</h4>
  <p>
- However, certain kinds of rules about the manner of distributing free
+ Certain kinds of rules about the manner of distributing free
  software are acceptable, when they don't conflict with the central
- freedoms.  For example, copyleft (very simply stated) is the rule that
+ freedoms.  For example, <a href="/copyleft/copyleft.html">copyleft</a>
- when redistributing the program, you cannot add restrictions to deny
+ (very simply stated) is the rule that when redistributing the program,
- other people the central freedoms.  This rule does not conflict with
+ you cannot add restrictions to deny other people the central freedoms.
- the central freedoms; rather it protects them.
+ This rule does not conflict with the central freedoms; rather it
+ protects them.
  </p>
  <p>
- In the GNU project, we use <a href="/copyleft/copyleft.html">
+ In the GNU project, we use copyleft to protect the four freedoms
- copyleft </a> to protect the four freedoms legally for everyone.  We
+ legally for everyone.  We believe there are important reasons why
- believe there are important reasons why
  <a href="/philosophy/pragmatic.html">it is better to use
  copyleft</a>.  However,
  <a href="/philosophy/categories.html#Non-CopyleftedFreeSoftware">
-Line 181 
 Software</a> for a description of how &l
+Line 261 
 Software</a> for a description of how &l
  relate to each other.
  </p>
- <p>
+ <h4>Rules about packaging and distribution details</h4>
- &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free
- program must be available for commercial use, commercial development,
- and commercial distribution.  Commercial development of free software
- is no longer unusual; such free commercial software is very important.
- You may have paid money to get copies of free software, or you may have
- obtained copies at no charge.  But regardless of how you got your copies,
- you always have the freedom to copy and change the software, even to
- <a href="/philosophy/selling.html">sell copies</a>.
- </p>
- <p>
- Whether a change constitutes an improvement is a subjective matter.
- If your right to modify a program is limited, in substance, to changes that
- someone else considers an improvement, that program is not free.
- </p>
  <p>
- However, rules about how to package a modified version are acceptable,
+ Rules about how to package a modified version are acceptable,
  if they don't substantively limit your freedom to release modified
  versions, or your freedom to make and use modified versions privately.
  Thus, it is acceptable for the license to require that you change the
-Line 231 
 sort of requirement is acceptable only i
+Line 296 
 sort of requirement is acceptable only i
  facility that allows you to specify the original program's name as an
  alias for the modified version.</p>
+ <h4>Export regulations</h4>
  <p>
  Sometimes government <a id="exportcontrol">export control regulations</a>
  and trade sanctions can constrain your freedom to distribute copies of
-Line 253 
 export law could make the requirement no
+Line 320 
 export law could make the requirement no
  software nonfree.
  </p>
+ <h4>Legal considerations</h4>
+ <p>
+ In order for these freedoms to be real, they must be permanent and
+ irrevocable as long as you do nothing wrong; if the developer of the
+ software has the power to revoke the license, or retroactively add
+ restrictions to its terms, without your doing anything wrong to give
+ cause, the software is not free.
+ </p>
  <p>
  A free license may not require compliance with the license of a
  nonfree program.  Thus, for instance, if a license requires you to
-Line 267 
 It is acceptable for a free license to s
+Line 344 
 It is acceptable for a free license to s
  law applies, or where litigation must be done, or both.
  </p>
+ <h4>Contract-based licenses</h4>
  <p>
  Most free software licenses are based on copyright, and there are limits
  on what kinds of requirements can be imposed through copyright.  If a
-Line 286 
 legitimate, we will have to think about
+Line 365 
 legitimate, we will have to think about
  it is nonfree.
  </p>
+ <h4>Use the right words when talking about free software</h4>
  <p>
  When talking about free software, it is best to avoid using terms
  like &ldquo;give away&rdquo; or &ldquo;for free,&rdquo; because those terms imply that
-Line 297 
 a list of proper <a href="/philosophy/fs
+Line 378 
 a list of proper <a href="/philosophy/fs
  &ldquo;free software&rdquo;</a> into various languages.
  </p>
+ <h4>How we interpret these criteria</h4>
  <p>
  Finally, note that criteria such as those stated in this free software
  definition require careful thought for their interpretation.  To decide
-Line 311 
 a conclusion about a new issue, we often
+Line 394 
 a conclusion about a new issue, we often
  it easier to see why certain licenses do or don't qualify.
  </p>
+ <h4>Get help with free licenses</h4>
  <p>
  If you are interested in whether a specific license qualifies as a free
  software license, see our <a href="/licenses/license-list.html">list
-Line 358 
 free cultural works</a> applicable to an
+Line 443 
 free cultural works</a> applicable to an
  <h3 id="open-source">Open Source?</h3>
  <p>
- Another group has started using the term &ldquo;open source&rdquo; to mean
+ Another group uses the term &ldquo;open source&rdquo; to mean
  something close (but not identical) to &ldquo;free software&rdquo;.  We
  prefer the term &ldquo;free software&rdquo; because, once you have heard that
  it refers to freedom rather than price, it calls to mind freedom.  The
  word &ldquo;open&rdquo; <a href="/philosophy/open-source-misses-the-point.html">
  never refers to freedom</a>.
  </p>
+ </div>
  <h3 id="History">History</h3>
-Line 374 
 was changed.</p>
+Line 460 
 was changed.</p>
  <ul>
+ <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.164&amp;r2=1.165">Version
+.165</a>: Clarify that arbitrary annoyances in the code do not
+ negate freedom 0, and that freedoms 1 and 3 enable users to remove them.</li>
+ <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.152&amp;r2=1.153">Version
+.153</a>: Clarify that freedom to run the program means nothing stops
+ you from making it run.</li>
+ <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.140&amp;r2=1.141">Version
+.141</a>: Clarify which code needs to be free.</li>
+ <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.134&amp;r2=1.135">Version
+.135</a>: Say each time that freedom 0 is the freedom to run the program
+ as you wish.</li>
+ <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.133&amp;r2=1.134">Version
+.134</a>: Freedom 0 is not a matter of the program's functionality.</li>
  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.130&amp;r2=1.131">Version
 .131</a>: A free license may not require compliance with a nonfree license
  of another program.</li>
-Line 470 
 licenses.</li>
+Line 574 
 licenses.</li>
  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.10&amp;r2=1.11">Version
 .11</a>: Note that a free license may require you to send a copy of
- versions you distribute to the author.</li>
+ versions you distribute to previous developers on request.</li>
  </ul>
-Line 482 
 You can review the complete list of chan
+Line 586 
 You can review the complete list of chan
  the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;view=log">cvsweb
  interface</a>.</p>
+ <h3 style="font-size:1em">Footnote</h3>
+ <ol>
+ <li id="f1">The reason they are numbered 0, 1, 2 and 3 is historical. Around
+there were three freedoms, numbered 1, 2 and 3. Then we realized that
+ the freedom to run the program needed to be mentioned explicitly.
+ It was clearly more basic than the other three, so it properly should
+ precede them. Rather than renumber the others, we made it freedom&nbsp;0.</li>
+ </ol>
  </div><!-- for id="content", starts in the include above -->
  <!--#include virtual="/server/footer.html" -->
-Line 515 
 of this article.</p>
+Line 627 
 of this article.</p>
  <!-- Regarding copyright, in general, standalone pages (as opposed to
       files generated as part of manuals) on the GNU web server should
-      be under CC BY-ND 3.0 US.  Please do NOT change or remove this
+      be under CC BY-ND 4.0.  Please do NOT change or remove this
       without talking with the webmasters or licensing team first.
       Please make sure the copyright date is consistent with the
       document.  For web pages, it is ok to list just the latest year the
-Line 530 
 of this article.</p>
+Line 642 
 of this article.</p>
       There is more detail about copyright years in the GNU Maintainers
       Information document, www.gnu.org/prep/maintain. -->
- <p>Copyright &copy; 1996-2002, 2004-2007, 2009, 2010, 2012, 2013
+ <p>Copyright &copy; 1996, 2002, 2004-2007, 2009-2019
  Free Software Foundation, Inc.</p>
  <p>This page is licensed under a <a rel="license"
- href="http://creativecommons.org/licenses/by-nd/3.0/us/">Creative
+ href="http://creativecommons.org/licenses/by-nd/4.0/">Creative
- Commons Attribution-NoDerivs 3.0 United States License</a>.</p>
+ Commons Attribution-NoDerivatives 4.0 International License</a>.</p>
  <!--#include virtual="/server/bottom-notes.html" -->
- <p></p><p class="unprintable">Updated:
+ <p class="unprintable">Updated:
  <!-- timestamp start -->
  $Date$
  <!-- timestamp end -->
  </p>
  </div>
- </div>
+ </div><!-- for class="inner", starts in the banner include -->
  </body>
  </html>

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