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1  <!--#include virtual="/server/header.html" -->  <!--#include virtual="/server/header.html" -->
2  <!-- Parent-Version: 1.75 -->  <!-- Parent-Version: 1.84 -->
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    
# Line 11  Line 11 
11    
12  <h2>What is free software?</h2>  <h2>What is free software?</h2>
13    
14    <blockquote class="note" id="fsf-licensing"><p style="font-size: 80%">
15    Have a question about free software licensing not answered here?
16    See our other <a href="http://www.fsf.org/licensing">licensing resources</a>,
17    and if necessary contact the FSF Compliance Lab
18    at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p>
19    </blockquote>
20    
21  <h3>The Free Software Definition</h3>  <h3>The Free Software Definition</h3>
22    
23  <blockquote>  <blockquote>
# Line 22  about subtle issues.  See the <a href="# Line 29  about subtle issues.  See the <a href="#
29  below for a list of changes that affect the definition of free  below for a list of changes that affect the definition of free
30  software.  software.
31  </p>  </p>
 </blockquote>  
32    
33  <p>  <p>
34  &ldquo;Free software&rdquo; means software that respects users'  &ldquo;Open source&rdquo; is something different: it has a very
35  freedom and community.  Roughly, <b>the users have the freedom to run,  different philosophy based on different values.  Its practical
36  copy, distribute, study, change and improve the software</b>.  definition is different too, but nearly all open source programs are
37    in fact free.  We explain the
38    difference <a href="/philosophy/open-source-misses-the-point.html">here</a>.
39  </p>  </p>
40    </blockquote>
41    
42  <p>  <p>
43  Thus, &ldquo;free software&rdquo; is a matter of liberty, not price.  &ldquo;Free software&rdquo; means software that respects users'
44  To understand the concept, you should think of &ldquo;free&rdquo; as  freedom and community.  Roughly, it means that <b>the users have the
45  in &ldquo;free speech,&rdquo; not as in &ldquo;free beer&rdquo;.  freedom to run, copy, distribute, study, change and improve the
46    software</b>.  Thus, &ldquo;free software&rdquo; is a matter of
47    liberty, not price.  To understand the concept, you should think of
48    &ldquo;free&rdquo; as in &ldquo;free speech,&rdquo; not as in
49    &ldquo;free beer&rdquo;.  We sometimes call it &ldquo;libre
50    software,&rdquo; borrowing the French or Spanish word for
51    &ldquo;free&rdquo; as in freedom, to show we do not mean the software
52    is gratis.
53  </p>  </p>
54    
55  <p>  <p>
56  With these freedoms, the users (both individually and collectively)  We campaign for these freedoms because everyone deserves them.  With
57  control the program and what it does for them.  When users don't  these freedoms, the users (both individually and collectively) control
58  control the program, the program controls the users.  The developer  the program and what it does for them.  When users don't control the
59  controls the program, and through it exercises power over the users.  program, we call it a &ldquo;nonfree&rdquo; or
60  Therefore, a &ldquo;nonfree&rdquo; or &ldquo;proprietary&rdquo; program  &ldquo;proprietary&rdquo; program.  The nonfree program controls the
61  is <a href="/philosophy/free-software-even-more-important.html"> an  users, and the developer controls the program; this makes the
62  instrument of unjust power</a>.  program <a href="/philosophy/free-software-even-more-important.html">
63    an instrument of unjust power</a>.
64  </p>  </p>
65    
66    <h4> The four essential freedoms</h4>
67    
68  <p>  <p>
69  A program is free software if the program's users have the  A program is free software if the program's users have the
70  four essential freedoms:  four essential freedoms:
71  </p>  </p>
72    
73  <ul>  <ul>
74    <li>The freedom to run the program, for any purpose (freedom 0).</li>    <li>The freedom to run the program as you wish,
75          for any purpose (freedom 0).</li>
76    <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
77        does your computing as you wish (freedom 1). Access to the source        does your computing as you wish (freedom 1). Access to the source
78        code is a precondition for this.        code is a precondition for this.
79    </li>    </li>
80    <li>The freedom to redistribute copies so you can help your neighbor    <li>The freedom to redistribute copies so you can help others
81        (freedom 2).        (freedom 2).
82    </li>    </li>
83    <li>The freedom to distribute copies of your modified versions    <li>The freedom to distribute copies of your modified versions
# Line 73  freedoms.  Otherwise, it is nonfree.  Wh Line 93  freedoms.  Otherwise, it is nonfree.  Wh
93  nonfree distribution schemes in terms of how far they fall short of  nonfree distribution schemes in terms of how far they fall short of
94  being free, we consider them all equally unethical.</p>  being free, we consider them all equally unethical.</p>
95    
96  <p>The rest of this page clarifies certain points about what makes  <p>In any given scenario, these freedoms must apply to whatever code
97  specific freedoms adequate or not.</p>  we plan to make use of, or lead others to make use of.  For instance,
98    consider a program A which automatically launches a program B to
99  <p>Freedom to distribute (freedoms 2 and 3) means you are free to  handle some cases.  If we plan to distribute A as it stands, that
100  redistribute copies, either with or without modifications, either  implies users will need B, so we need to judge whether both A and B
101  gratis or charging a fee for distribution, to  are free.  However, if we plan to modify A so that it doesn't use B,
102  <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these  only A needs to be free; B is not pertinent to that plan.</p>
 things means (among other things) that you do not have to ask or pay  
 for permission to do so.  
 </p>  
103    
104  <p>  <p>
105  You should also have the freedom to make modifications and use them  &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free
106  privately in your own work or play, without even mentioning that they  program must be available for commercial use, commercial development,
107  exist.  If you do publish your changes, you should not be required to  and commercial distribution.  Commercial development of free software
108  notify anyone in particular, or in any particular way.  is no longer unusual; such free commercial software is very important.
109    You may have paid money to get copies of free software, or you may have
110    obtained copies at no charge.  But regardless of how you got your copies,
111    you always have the freedom to copy and change the software, even to
112    <a href="/philosophy/selling.html">sell copies</a>.
113  </p>  </p>
114    
115    <p>The rest of this page clarifies certain points about what makes
116    specific freedoms adequate or not.</p>
117    
118    <h4>The freedom to run the program as you wish</h4>
119    
120  <p>  <p>
121  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
122  or organization to use it on any kind of computer system, for any kind of  or organization to use it on any kind of computer system, for any kind of
# Line 103  for her purposes, but you are not entitl Line 129  for her purposes, but you are not entitl
129  </p>  </p>
130    
131  <p>  <p>
132  The freedom to redistribute copies must include binary or executable  The freedom to run the program as you wish means that you are not
133  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
134  unmodified versions.  (Distributing programs in runnable form is necessary  functionality the program has, whether it is technically capable of
135  for conveniently installable free operating systems.)  It is OK if there  functioning in any given environment, or whether it is useful for any
136  is no way to produce a binary or executable form for a certain program  particular computing activity.</p>
137  (since some languages don't support that feature), but you must have the  
138  freedom to redistribute such forms should you find or develop a way to  <h4>The freedom to study the source code and make changes</h4>
 make them.  
 </p>  
139    
140  <p>  <p>
141  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 128  the original.  If the program is deliver Line 152  the original.  If the program is deliver
152  run someone else's modified versions but refuse to run yours &mdash; a  run someone else's modified versions but refuse to run yours &mdash; a
153  practice known as &ldquo;tivoization&rdquo; or &ldquo;lockdown&rdquo;,  practice known as &ldquo;tivoization&rdquo; or &ldquo;lockdown&rdquo;,
154  or (in its practitioners' perverse terminology) as &ldquo;secure  or (in its practitioners' perverse terminology) as &ldquo;secure
155  boot&rdquo; &mdash; freedom 1 becomes a theoretical fiction rather  boot&rdquo; &mdash; freedom 1 becomes an empty pretense rather than a
156  than a practical freedom.  This is not sufficient.  In other words,  practical reality.  These binaries are not free
157  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.  
158  </p>  </p>
159    
160  <p>  <p>
# Line 143  license is too restrictive to qualify as Line 166  license is too restrictive to qualify as
166  </p>  </p>
167    
168  <p>  <p>
169    Whether a change constitutes an improvement is a subjective matter.
170    If your right to modify a program is limited, in substance, to changes that
171    someone else considers an improvement, that program is not free.
172    </p>
173    
174    <h4>The freedom to redistribute if you wish: basic requirements</h4>
175    
176    <p>Freedom to distribute (freedoms 2 and 3) means you are free to
177    redistribute copies, either with or without modifications, either
178    gratis or charging a fee for distribution, to
179    <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these
180    things means (among other things) that you do not have to ask or pay
181    for permission to do so.
182    </p>
183    
184    <p>
185    You should also have the freedom to make modifications and use them
186    privately in your own work or play, without even mentioning that they
187    exist.  If you do publish your changes, you should not be required to
188    notify anyone in particular, or in any particular way.
189    </p>
190    
191    <p>
192  Freedom 3 includes the freedom to release your modified versions  Freedom 3 includes the freedom to release your modified versions
193  as free software.  A free license may also permit other ways of  as free software.  A free license may also permit other ways of
194  releasing them; in other words, it does not have to be  releasing them; in other words, it does not have to be
# Line 152  as a free license. Line 198  as a free license.
198  </p>  </p>
199    
200  <p>  <p>
201  In order for these freedoms to be real, they must be permanent and  The freedom to redistribute copies must include binary or executable
202  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
203  software has the power to revoke the license, or retroactively add  unmodified versions.  (Distributing programs in runnable form is necessary
204  restrictions to its terms, without your doing anything wrong to give  for conveniently installable free operating systems.)  It is OK if there
205  cause, the software is not free.  is no way to produce a binary or executable form for a certain program
206    (since some languages don't support that feature), but you must have the
207    freedom to redistribute such forms should you find or develop a way to
208    make them.
209  </p>  </p>
210    
211    <h4>Copyleft</h4>
212    
213  <p>  <p>
214  However, certain kinds of rules about the manner of distributing free  Certain kinds of rules about the manner of distributing free
215  software are acceptable, when they don't conflict with the central  software are acceptable, when they don't conflict with the central
216  freedoms.  For example, copyleft (very simply stated) is the rule that  freedoms.  For example, <a href="/copyleft/copyleft.html">copyleft</a>
217  when redistributing the program, you cannot add restrictions to deny  (very simply stated) is the rule that when redistributing the program,
218  other people the central freedoms.  This rule does not conflict with  you cannot add restrictions to deny other people the central freedoms.
219  the central freedoms; rather it protects them.  This rule does not conflict with the central freedoms; rather it
220    protects them.
221  </p>  </p>
222    
223  <p>  <p>
224  &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free  In the GNU project, we use copyleft to protect the four freedoms
225  program must be available for commercial use, commercial development,  legally for everyone.  We believe there are important reasons why
226  and commercial distribution.  Commercial development of free software  <a href="/philosophy/pragmatic.html">it is better to use
227  is no longer unusual; such free commercial software is very important.  copyleft</a>.  However,
228  You may have paid money to get copies of free software, or you may have  <a href="/philosophy/categories.html#Non-CopyleftedFreeSoftware">
229  obtained copies at no charge.  But regardless of how you got your copies,  noncopylefted free software</a> is ethical
230  you always have the freedom to copy and change the software, even to  too.  See <a href="/philosophy/categories.html">Categories of Free
231  <a href="/philosophy/selling.html">sell copies</a>.  Software</a> for a description of how &ldquo;free software,&rdquo;
232    &ldquo;copylefted software&rdquo; and other categories of software
233    relate to each other.
234  </p>  </p>
235    
236  <p>  <h4>Rules about packaging and distribution details</h4>
 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>  
237    
238  <p>  <p>
239  However, rules about how to package a modified version are acceptable,  Rules about how to package a modified version are acceptable,
240  if they don't substantively limit your freedom to release modified  if they don't substantively limit your freedom to release modified
241  versions, or your freedom to make and use modified versions privately.  versions, or your freedom to make and use modified versions privately.
242  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 218  sort of requirement is acceptable only i Line 268  sort of requirement is acceptable only i
268  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
269  alias for the modified version.</p>  alias for the modified version.</p>
270    
271  <p>  <h4>Export regulations</h4>
 In the GNU project, we use  
 <a href="/copyleft/copyleft.html">copyleft</a>  
 to protect these freedoms legally for everyone.  But  
 <a href="/philosophy/categories.html#Non-CopyleftedFreeSoftware">noncopylefted  
 free software</a> also exists.  We believe there are important reasons why  
 <a href="/philosophy/pragmatic.html">it is better to use copyleft</a>,  
 but if your program is noncopylefted free software, it is still basically  
 ethical. (See <a href="/philosophy/categories.html">Categories of Free Software</a> for a description of how &ldquo;free software,&rdquo; &ldquo;copylefted software&rdquo; and other categories of software relate to each other.)  
 </p>  
272    
273  <p>  <p>
274  Sometimes government <a id="exportcontrol">export control regulations</a>  Sometimes government <a id="exportcontrol">export control regulations</a>
# Line 251  export law could make the requirement no Line 292  export law could make the requirement no
292  software nonfree.  software nonfree.
293  </p>  </p>
294    
295    <h4>Legal considerations</h4>
296    
297    <p>
298    In order for these freedoms to be real, they must be permanent and
299    irrevocable as long as you do nothing wrong; if the developer of the
300    software has the power to revoke the license, or retroactively add
301    restrictions to its terms, without your doing anything wrong to give
302    cause, the software is not free.
303    </p>
304    
305    <p>
306    A free license may not require compliance with the license of a
307    nonfree program.  Thus, for instance, if a license requires you to
308    comply with the licenses of &ldquo;all the programs you use&rdquo;, in
309    the case of a user that runs nonfree programs this would require
310    compliance with the licenses of those nonfree programs; that makes the
311    license nonfree.
312    </p>
313    
314    <p>
315    It is acceptable for a free license to specify which jurisdiction's
316    law applies, or where litigation must be done, or both.
317    </p>
318    
319    <h4>Contract-based licenses</h4>
320    
321  <p>  <p>
322  Most free software licenses are based on copyright, and there are limits  Most free software licenses are based on copyright, and there are limits
323  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 270  legitimate, we will have to think about Line 337  legitimate, we will have to think about
337  it is nonfree.  it is nonfree.
338  </p>  </p>
339    
340    <h4>Use the right words when talking about free software</h4>
341    
342  <p>  <p>
343  When talking about free software, it is best to avoid using terms  When talking about free software, it is best to avoid using terms
344  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 281  a list of proper <a href="/philosophy/fs Line 350  a list of proper <a href="/philosophy/fs
350  &ldquo;free software&rdquo;</a> into various languages.  &ldquo;free software&rdquo;</a> into various languages.
351  </p>  </p>
352    
353    <h4>How we interpret these criteria</h4>
354    
355  <p>  <p>
356  Finally, note that criteria such as those stated in this free software  Finally, note that criteria such as those stated in this free software
357  definition require careful thought for their interpretation.  To decide  definition require careful thought for their interpretation.  To decide
# Line 295  a conclusion about a new issue, we often Line 366  a conclusion about a new issue, we often
366  it easier to see why certain licenses do or don't qualify.  it easier to see why certain licenses do or don't qualify.
367  </p>  </p>
368    
369    <h4>Get help with free licenses</h4>
370    
371  <p>  <p>
372  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
373  software license, see our <a href="/licenses/license-list.html">list  software license, see our <a href="/licenses/license-list.html">list
# Line 342  free cultural works</a> applicable to an Line 415  free cultural works</a> applicable to an
415  <h3 id="open-source">Open Source?</h3>  <h3 id="open-source">Open Source?</h3>
416    
417  <p>  <p>
418  Another group has started using the term &ldquo;open source&rdquo; to mean  Another group uses the term &ldquo;open source&rdquo; to mean
419  something close (but not identical) to &ldquo;free software&rdquo;.  We  something close (but not identical) to &ldquo;free software&rdquo;.  We
420  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
421  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
# Line 358  was changed.</p> Line 431  was changed.</p>
431    
432  <ul>  <ul>
433    
434    <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
435    1.153</a>: Clarify that freedom to run the program means nothing stops
436    you from making it run.</li>
437    
438    <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
439    1.141</a>: Clarify which code needs to be free.</li>
440    
441    <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
442    1.135</a>: Say each time that freedom 0 is the freedom to run the program
443    as you wish.</li>
444    
445    <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
446    1.134</a>: Freedom 0 is not a matter of the program's functionality.</li>
447    
448    <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
449    1.131</a>: A free license may not require compliance with a nonfree license
450    of another program.</li>
451    
452    <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.128&amp;r2=1.129">Version
453    1.129</a>: State explicitly that choice of law and choice of forum
454    specifications are allowed.  (This was always our policy.)</li>
455    
456  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.121&amp;r2=1.122">Version  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.121&amp;r2=1.122">Version
457  1.122</a>: An export control requirement is a real problem if the  1.122</a>: An export control requirement is a real problem if the
458  requirement is nontrivial; otherwise it is only a potential problem.</li>  requirement is nontrivial; otherwise it is only a potential problem.</li>
# Line 446  licenses.</li> Line 541  licenses.</li>
541    
542  <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
543  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
544  versions you distribute to the author.</li>  versions you distribute to previous developers on request.</li>
545    
546  </ul>  </ul>
547    
# Line 462  interface</a>.</p> Line 557  interface</a>.</p>
557  </div><!-- for id="content", starts in the include above -->  </div><!-- for id="content", starts in the include above -->
558  <!--#include virtual="/server/footer.html" -->  <!--#include virtual="/server/footer.html" -->
559  <div id="footer">  <div id="footer">
560    <div class="unprintable">
561    
562  <p>Please send general FSF &amp; GNU inquiries to  <p>Please send general FSF &amp; GNU inquiries to
563  <a href="mailto:gnu@gnu.org">&lt;gnu@gnu.org&gt;</a>.  <a href="mailto:gnu@gnu.org">&lt;gnu@gnu.org&gt;</a>.
# Line 486  Please see the <a Line 582  Please see the <a
582  href="/server/standards/README.translations.html">Translations  href="/server/standards/README.translations.html">Translations
583  README</a> for information on coordinating and submitting translations  README</a> for information on coordinating and submitting translations
584  of this article.</p>  of this article.</p>
585    </div>
586    
587  <!-- Regarding copyright, in general, standalone pages (as opposed to  <!-- Regarding copyright, in general, standalone pages (as opposed to
588       files generated as part of manuals) on the GNU web server should       files generated as part of manuals) on the GNU web server should
589       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
590       without talking with the webmasters or licensing team first.       without talking with the webmasters or licensing team first.
591       Please make sure the copyright date is consistent with the       Please make sure the copyright date is consistent with the
592       document.  For web pages, it is ok to list just the latest year the       document.  For web pages, it is ok to list just the latest year the
# Line 504  of this article.</p> Line 601  of this article.</p>
601       There is more detail about copyright years in the GNU Maintainers       There is more detail about copyright years in the GNU Maintainers
602       Information document, www.gnu.org/prep/maintain. -->       Information document, www.gnu.org/prep/maintain. -->
603    
604  <p>Copyright &copy; 1996-2002, 2004-2007, 2009, 2010, 2012, 2013  <p>Copyright &copy; 1996, 2002, 2004-2007, 2009-2018
605  Free Software Foundation, Inc.</p>  Free Software Foundation, Inc.</p>
606    
607  <p>This page is licensed under a <a rel="license"  <p>This page is licensed under a <a rel="license"
608  href="http://creativecommons.org/licenses/by-nd/3.0/us/">Creative  href="http://creativecommons.org/licenses/by-nd/4.0/">Creative
609  Commons Attribution-NoDerivs 3.0 United States License</a>.</p>  Commons Attribution-NoDerivatives 4.0 International License</a>.</p>
610    
611  <!--#include virtual="/server/bottom-notes.html" -->  <!--#include virtual="/server/bottom-notes.html" -->
612    
613  <p>Updated:  <p class="unprintable">Updated:
614  <!-- timestamp start -->  <!-- timestamp start -->
615  $Date$  $Date$
616  <!-- timestamp end -->  <!-- timestamp end -->

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