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1  <!--#include virtual="/server/header.html" -->  <!--#include virtual="/server/header.html" -->
2  <!-- Parent-Version: 1.77 -->  <!-- Parent-Version: 1.85 -->
3  <title>What is free software?  <title>What is free software?
4  - GNU Project - Free Software Foundation</title>  - GNU Project - Free Software Foundation</title>
5    <style type="text/css" media="print,screen"><!--
6    .note { margin-left: 6%; margin-right: 6%; }
7    @media (min-width: 48em) {
8       .note { margin-top: .8em; }
9    }
10    --></style>
11  <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="Keywords" content="GNU, FSF, Free Software Foundation, Linux, Emacs, GCC, Unix, Free Software, Operating System, GNU Kernel, HURD, GNU HURD, Hurd" />
12  <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." />  <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." />
13    
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15  <!--#include virtual="/server/banner.html" -->  <!--#include virtual="/server/banner.html" -->
16    
17  <h2>What is free software?</h2>  <h2>What is free software?</h2>
 <!--#include virtual="/licenses/fsf-licensing.html" -->  
18    
19    <div class="article">
20  <h3>The Free Software Definition</h3>  <h3>The Free Software Definition</h3>
21    
22  <blockquote>  <blockquote class="note" id="fsf-licensing"><p style="font-size: 80%">
23    Have a question about free software licensing not answered here?
24    See our other <a href="http://www.fsf.org/licensing">licensing resources</a>,
25    and if necessary contact the FSF Compliance Lab
26    at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p>
27    </blockquote>
28    
29    <div class="comment">
30  <p>  <p>
31  The free software definition presents the criteria for whether a  The free software definition presents the criteria for whether a
32  particular software program qualifies as free software.  From time to  particular software program qualifies as free software.  From time to
# Line 23  about subtle issues.  See the <a href="# Line 35  about subtle issues.  See the <a href="#
35  below for a list of changes that affect the definition of free  below for a list of changes that affect the definition of free
36  software.  software.
37  </p>  </p>
38  </blockquote>  
39    <p>
40    &ldquo;Open source&rdquo; is something different: it has a very
41    different philosophy based on different values.  Its practical
42    definition is different too, but nearly all open source programs are
43    in fact free.  We explain the
44    difference in <a href="/philosophy/open-source-misses-the-point.html">
45    Why &ldquo;Open Source&rdquo; misses the point of Free Software</a>.
46    </p>
47    </div>
48    
49  <p>  <p>
50  &ldquo;Free software&rdquo; means software that respects users'  &ldquo;Free software&rdquo; means software that respects users'
# Line 33  software</b>.  Thus, &ldquo;free softwar Line 54  software</b>.  Thus, &ldquo;free softwar
54  liberty, not price.  To understand the concept, you should think of  liberty, not price.  To understand the concept, you should think of
55  &ldquo;free&rdquo; as in &ldquo;free speech,&rdquo; not as in  &ldquo;free&rdquo; as in &ldquo;free speech,&rdquo; not as in
56  &ldquo;free beer&rdquo;.  We sometimes call it &ldquo;libre  &ldquo;free beer&rdquo;.  We sometimes call it &ldquo;libre
57  software&rdquo; to show we do not mean it is gratis.  software,&rdquo; borrowing the French or Spanish word for
58    &ldquo;free&rdquo; as in freedom, to show we do not mean the software
59    is gratis.
60  </p>  </p>
61    
62  <p>  <p>
# Line 47  program <a href="/philosophy/free-softwa Line 70  program <a href="/philosophy/free-softwa
70  an instrument of unjust power</a>.  an instrument of unjust power</a>.
71  </p>  </p>
72    
73    <h4> The four essential freedoms</h4>
74    
75  <p>  <p>
76  A program is free software if the program's users have the  A program is free software if the program's users have the
77  four essential freedoms:  four essential freedoms: <a href="#f1">[1]</a>
78  </p>  </p>
79    
80  <ul>  <ul class="important">
81    <li>The freedom to run the program as you wish,    <li>The freedom to run the program as you wish,
82        for any purpose (freedom 0).</li>        for any purpose (freedom 0).</li>
83    <li>The freedom to study how the program works, and change it so it    <li>The freedom to study how the program works, and change it so it
84        does your computing as you wish (freedom 1). Access to the source        does your computing as you wish (freedom 1). Access to the source
85        code is a precondition for this.        code is a precondition for this.
86    </li>    </li>
87    <li>The freedom to redistribute copies so you can help your neighbor    <li>The freedom to redistribute copies so you can help others
88        (freedom 2).        (freedom 2).
89    </li>    </li>
90    <li>The freedom to distribute copies of your modified versions    <li>The freedom to distribute copies of your modified versions
# Line 81  consider a program A which automatically Line 106  consider a program A which automatically
106  handle some cases.  If we plan to distribute A as it stands, that  handle some cases.  If we plan to distribute A as it stands, that
107  implies users will need B, so we need to judge whether both A and B  implies users will need B, so we need to judge whether both A and B
108  are free.  However, if we plan to modify A so that it doesn't use B,  are free.  However, if we plan to modify A so that it doesn't use B,
109  only A needs to be free; we can ignore B.</p>  only A needs to be free; B is not pertinent to that plan.</p>
110    
111    <p>
112    &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free
113    program must be available for commercial use, commercial development,
114    and commercial distribution.  Commercial development of free software
115    is no longer unusual; such free commercial software is very important.
116    You may have paid money to get copies of free software, or you may have
117    obtained copies at no charge.  But regardless of how you got your copies,
118    you always have the freedom to copy and change the software, even to
119    <a href="/philosophy/selling.html">sell copies</a>.
120    </p>
121    
122  <p>The rest of this page clarifies certain points about what makes  <p>The rest of this page clarifies certain points about what makes
123  specific freedoms adequate or not.</p>  specific freedoms adequate or not.</p>
124    
125  <p>Freedom to distribute (freedoms 2 and 3) means you are free to  <h4>The freedom to run the program as you wish</h4>
 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>  
126    
127  <p>  <p>
128  The freedom to run the program means the freedom for any kind of person  The freedom to run the program means the freedom for any kind of person
# Line 114  for her purposes, but you are not entitl Line 137  for her purposes, but you are not entitl
137    
138  <p>  <p>
139  The freedom to run the program as you wish means that you are not  The freedom to run the program as you wish means that you are not
140  forbidden or stopped from doing so.  It has nothing to do with what  forbidden or stopped from making it run.  This has nothing to do with what
141  functionality the program has, or whether it is useful for what you  functionality the program has, whether it is technically capable of
142  want to do.</p>  functioning in any given environment, or whether it is useful for any
143    particular computing activity.</p>
144    
145  <p>  <h4>The freedom to study the source code and make changes</h4>
 The freedom to redistribute copies must include binary or executable  
 forms of the program, as well as source code, for both modified and  
 unmodified versions.  (Distributing programs in runnable form is necessary  
 for conveniently installable free operating systems.)  It is OK if there  
 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>  
146    
147  <p>  <p>
148  In order for freedoms 1 and 3 (the freedom to make changes and the  In order for freedoms 1 and 3 (the freedom to make changes and the
# Line 158  license is too restrictive to qualify as Line 173  license is too restrictive to qualify as
173  </p>  </p>
174    
175  <p>  <p>
176    Whether a change constitutes an improvement is a subjective matter.
177    If your right to modify a program is limited, in substance, to changes that
178    someone else considers an improvement, that program is not free.
179    </p>
180    
181    <h4>The freedom to redistribute if you wish: basic requirements</h4>
182    
183    <p>Freedom to distribute (freedoms 2 and 3) means you are free to
184    redistribute copies, either with or without modifications, either
185    gratis or charging a fee for distribution, to
186    <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these
187    things means (among other things) that you do not have to ask or pay
188    for permission to do so.
189    </p>
190    
191    <p>
192    You should also have the freedom to make modifications and use them
193    privately in your own work or play, without even mentioning that they
194    exist.  If you do publish your changes, you should not be required to
195    notify anyone in particular, or in any particular way.
196    </p>
197    
198    <p>
199  Freedom 3 includes the freedom to release your modified versions  Freedom 3 includes the freedom to release your modified versions
200  as free software.  A free license may also permit other ways of  as free software.  A free license may also permit other ways of
201  releasing them; in other words, it does not have to be  releasing them; in other words, it does not have to be
# Line 167  as a free license. Line 205  as a free license.
205  </p>  </p>
206    
207  <p>  <p>
208  In order for these freedoms to be real, they must be permanent and  The freedom to redistribute copies must include binary or executable
209  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
210  software has the power to revoke the license, or retroactively add  unmodified versions.  (Distributing programs in runnable form is necessary
211  restrictions to its terms, without your doing anything wrong to give  for conveniently installable free operating systems.)  It is OK if there
212  cause, the software is not free.  is no way to produce a binary or executable form for a certain program
213    (since some languages don't support that feature), but you must have the
214    freedom to redistribute such forms should you find or develop a way to
215    make them.
216  </p>  </p>
217    
218    <h4>Copyleft</h4>
219    
220  <p>  <p>
221  However, certain kinds of rules about the manner of distributing free  Certain kinds of rules about the manner of distributing free
222  software are acceptable, when they don't conflict with the central  software are acceptable, when they don't conflict with the central
223  freedoms.  For example, <a href="/copyleft/copyleft.html">copyleft</a>  freedoms.  For example, <a href="/copyleft/copyleft.html">copyleft</a>
224  (very simply stated) is the rule that when redistributing the program,  (very simply stated) is the rule that when redistributing the program,
# Line 197  Software</a> for a description of how &l Line 240  Software</a> for a description of how &l
240  relate to each other.  relate to each other.
241  </p>  </p>
242    
243  <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>  
244    
245  <p>  <p>
246  However, rules about how to package a modified version are acceptable,  Rules about how to package a modified version are acceptable,
247  if they don't substantively limit your freedom to release modified  if they don't substantively limit your freedom to release modified
248  versions, or your freedom to make and use modified versions privately.  versions, or your freedom to make and use modified versions privately.
249  Thus, it is acceptable for the license to require that you change the  Thus, it is acceptable for the license to require that you change the
# Line 247  sort of requirement is acceptable only i Line 275  sort of requirement is acceptable only i
275  facility that allows you to specify the original program's name as an  facility that allows you to specify the original program's name as an
276  alias for the modified version.</p>  alias for the modified version.</p>
277    
278    <h4>Export regulations</h4>
279    
280  <p>  <p>
281  Sometimes government <a id="exportcontrol">export control regulations</a>  Sometimes government <a id="exportcontrol">export control regulations</a>
282  and trade sanctions can constrain your freedom to distribute copies of  and trade sanctions can constrain your freedom to distribute copies of
# Line 269  export law could make the requirement no Line 299  export law could make the requirement no
299  software nonfree.  software nonfree.
300  </p>  </p>
301    
302    <h4>Legal considerations</h4>
303    
304    <p>
305    In order for these freedoms to be real, they must be permanent and
306    irrevocable as long as you do nothing wrong; if the developer of the
307    software has the power to revoke the license, or retroactively add
308    restrictions to its terms, without your doing anything wrong to give
309    cause, the software is not free.
310    </p>
311    
312  <p>  <p>
313  A free license may not require compliance with the license of a  A free license may not require compliance with the license of a
314  nonfree program.  Thus, for instance, if a license requires you to  nonfree program.  Thus, for instance, if a license requires you to
# Line 283  It is acceptable for a free license to s Line 323  It is acceptable for a free license to s
323  law applies, or where litigation must be done, or both.  law applies, or where litigation must be done, or both.
324  </p>  </p>
325    
326    <h4>Contract-based licenses</h4>
327    
328  <p>  <p>
329  Most free software licenses are based on copyright, and there are limits  Most free software licenses are based on copyright, and there are limits
330  on what kinds of requirements can be imposed through copyright.  If a  on what kinds of requirements can be imposed through copyright.  If a
# Line 302  legitimate, we will have to think about Line 344  legitimate, we will have to think about
344  it is nonfree.  it is nonfree.
345  </p>  </p>
346    
347    <h4>Use the right words when talking about free software</h4>
348    
349  <p>  <p>
350  When talking about free software, it is best to avoid using terms  When talking about free software, it is best to avoid using terms
351  like &ldquo;give away&rdquo; or &ldquo;for free,&rdquo; because those terms imply that  like &ldquo;give away&rdquo; or &ldquo;for free,&rdquo; because those terms imply that
# Line 313  a list of proper <a href="/philosophy/fs Line 357  a list of proper <a href="/philosophy/fs
357  &ldquo;free software&rdquo;</a> into various languages.  &ldquo;free software&rdquo;</a> into various languages.
358  </p>  </p>
359    
360    <h4>How we interpret these criteria</h4>
361    
362  <p>  <p>
363  Finally, note that criteria such as those stated in this free software  Finally, note that criteria such as those stated in this free software
364  definition require careful thought for their interpretation.  To decide  definition require careful thought for their interpretation.  To decide
# Line 327  a conclusion about a new issue, we often Line 373  a conclusion about a new issue, we often
373  it easier to see why certain licenses do or don't qualify.  it easier to see why certain licenses do or don't qualify.
374  </p>  </p>
375    
376    <h4>Get help with free licenses</h4>
377    
378  <p>  <p>
379  If you are interested in whether a specific license qualifies as a free  If you are interested in whether a specific license qualifies as a free
380  software license, see our <a href="/licenses/license-list.html">list  software license, see our <a href="/licenses/license-list.html">list
# Line 374  free cultural works</a> applicable to an Line 422  free cultural works</a> applicable to an
422  <h3 id="open-source">Open Source?</h3>  <h3 id="open-source">Open Source?</h3>
423    
424  <p>  <p>
425  Another group has started using the term &ldquo;open source&rdquo; to mean  Another group uses the term &ldquo;open source&rdquo; to mean
426  something close (but not identical) to &ldquo;free software&rdquo;.  We  something close (but not identical) to &ldquo;free software&rdquo;.  We
427  prefer the term &ldquo;free software&rdquo; because, once you have heard that  prefer the term &ldquo;free software&rdquo; because, once you have heard that
428  it refers to freedom rather than price, it calls to mind freedom.  The  it refers to freedom rather than price, it calls to mind freedom.  The
429  word &ldquo;open&rdquo; <a href="/philosophy/open-source-misses-the-point.html">  word &ldquo;open&rdquo; <a href="/philosophy/open-source-misses-the-point.html">
430  never refers to freedom</a>.  never refers to freedom</a>.
431  </p>  </p>
432    </div>
433    
434  <h3 id="History">History</h3>  <h3 id="History">History</h3>
435    
# Line 390  was changed.</p> Line 439  was changed.</p>
439    
440  <ul>  <ul>
441    
442    <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
443    1.153</a>: Clarify that freedom to run the program means nothing stops
444    you from making it run.</li>
445    
446  <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  <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
447  1.141</a>: Clarify which code needs to be free.</li>  1.141</a>: Clarify which code needs to be free.</li>
448    
# Line 496  licenses.</li> Line 549  licenses.</li>
549    
550  <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  <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
551  1.11</a>: Note that a free license may require you to send a copy of  1.11</a>: Note that a free license may require you to send a copy of
552  versions you distribute to the author.</li>  versions you distribute to previous developers on request.</li>
553    
554  </ul>  </ul>
555    
# Line 508  You can review the complete list of chan Line 561  You can review the complete list of chan
561  the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;view=log">cvsweb  the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;view=log">cvsweb
562  interface</a>.</p>  interface</a>.</p>
563    
564    <h3 style="font-size:1em">Footnote</h3>
565    <ol>
566    <li id="f1">The reason they are numbered 0, 1, 2 and 3 is historical. Around
567    1990 there were three freedoms, numbered 1, 2 and 3. Then we realized that
568    the freedom to run the program needed to be mentioned explicitly.
569    It was clearly more basic than the other three, so it properly should
570    precede them. Rather than renumber the others, we made it freedom&nbsp;0.</li>
571    </ol>
572    
573  </div><!-- for id="content", starts in the include above -->  </div><!-- for id="content", starts in the include above -->
574  <!--#include virtual="/server/footer.html" -->  <!--#include virtual="/server/footer.html" -->
# Line 556  of this article.</p> Line 617  of this article.</p>
617       There is more detail about copyright years in the GNU Maintainers       There is more detail about copyright years in the GNU Maintainers
618       Information document, www.gnu.org/prep/maintain. -->       Information document, www.gnu.org/prep/maintain. -->
619    
620  <p>Copyright &copy; 1996-2002, 2004-2007, 2009, 2010, 2012, 2013, 2015  <p>Copyright &copy; 1996, 2002, 2004-2007, 2009-2018
621  Free Software Foundation, Inc.</p>  Free Software Foundation, Inc.</p>
622    
623  <p>This page is licensed under a <a rel="license"  <p>This page is licensed under a <a rel="license"

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