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21    <h2>What is Free Software?</h2>
22    <div class="thin"></div>
23    
24  <h2>What is free software?</h2>  <div class="important">
   
 <h3>The Free Software Definition</h3>  
   
 <blockquote>  
25  <p>  <p>
26  The free software definition presents the criteria for whether a  &ldquo;Free software&rdquo; means software that respects users'
27  particular software program qualifies as free software.  From time to  freedom and community.  Roughly, it means that <b>the users have the
28  time we revise this definition, to clarify it or to resolve questions  freedom to run, copy, distribute, study, change and improve the
29  about subtle issues.  See the <a href="#History">History section</a>  software</b>.  Thus, &ldquo;free software&rdquo; is a matter of
30  below for a list of changes that affect the definition of free  liberty, not price.  To understand the concept, you should think of
31  software.  &ldquo;free&rdquo; as in &ldquo;free speech,&rdquo; not as in
32    &ldquo;free beer.&rdquo;  We sometimes call it &ldquo;libre
33    software,&rdquo; borrowing the French or Spanish word for
34    &ldquo;free&rdquo; as in freedom, to show we do not mean the software
35    is gratis.
36  </p>  </p>
 </blockquote>  
37    
38  <p>  <p>
39  &ldquo;Free software&rdquo; means software that respects users'  You may have paid money to get copies of a free program, or you may
40  freedom and community.  Roughly, <b>the users have the freedom to run,  have obtained copies at no charge.  But regardless of how you got your
41  copy, distribute, study, change and improve the software</b>.  With these  copies, you always have the freedom to copy and change the software,
42  freedoms, the users (both individually and collectively) control the  even to <a href="/philosophy/selling.html">sell copies</a>.
 program and what it does for them.  
43  </p>  </p>
44    </div>
45    
46  <p>  <p>
47  When users don't control the program, the program controls the users.  We campaign for these freedoms because everyone deserves them.  With
48  The developer controls the program, and through it controls the users.  these freedoms, the users (both individually and collectively) control
49  This nonfree or &ldquo;proprietary&rdquo; program is therefore an  the program and what it does for them.  When users don't control the
50  instrument of unjust power.  program, we call it a &ldquo;nonfree&rdquo; or
51    &ldquo;proprietary&rdquo; program.  The nonfree program controls the
52    users, and the developer controls the program; this makes the
53    program <a href="/philosophy/free-software-even-more-important.html">
54    an instrument of unjust power</a>.
55  </p>  </p>
56    
57  <p>  <p>
58  Thus, &ldquo;free software&rdquo; is a matter of liberty, not price.  &ldquo;Open source&rdquo; is something different: it has a very
59  To understand the concept, you should think of &ldquo;free&rdquo; as  different philosophy based on different values.  Its practical
60  in &ldquo;free speech,&rdquo; not as in &ldquo;free beer&rdquo;.  definition is different too, but nearly all open source programs are
61    in fact free.  We explain the
62    difference in <a href="/philosophy/open-source-misses-the-point.html">
63    Why &ldquo;Open Source&rdquo; misses the point of Free Software</a>.
64    </p>
65    
66    <div class="toc">
67    <hr class="no-display" />
68    <h3 class="no-display">Table of contents</h3>
69    <ul>
70     <li><a href="#fs-definition">The Free Software Definition</a>
71      <ul>
72       <li><a href="#four-freedoms">The four essential freedoms</a></li>
73       <li><a href="#selling">Free software <em>can</em> be commercial</a></li>
74      </ul>
75     </li>
76     <li><a href="#clarifying">Clarifying the Boundary Between Free and Nonfree</a>
77      <ul>
78       <li><a href="#run-the-program">The freedom to run the program as you
79         wish</a></li>
80       <li><a href="#make-changes">The freedom to study the source code and make
81         changes</a></li>
82       <li><a href="#redistribute">The freedom to redistribute if you wish:
83         basic requirements</a></li>
84       <li><a href="#copyleft">Copyleft</a></li>
85       <li><a href="#packaging">Rules about packaging and distribution
86         details</a></li>
87       <li><a href="#exportcontrol">Export regulations</a></li>
88       <li><a href="#legal-details">Legal considerations</a></li>
89       <li><a href="#contracts">Contract-based licenses</a></li>
90      </ul>
91     </li>
92     <li><a href="#in-practice">The Free Software Definition in Practice</a>
93      <ul>
94       <li><a href="#interpretation">How we interpret these criteria</a></li>
95       <li><a href="#get-help">Get help with free licenses</a></li>
96       <li><a href="#terminology">Use the right words when talking about free
97         software</a></li>
98      </ul>
99     </li>
100     <li><a href="#beyond-software">Beyond Software</a></li>
101     <li><a href="#History">History</a></li>
102    </ul>
103    </div>
104    
105    <div class="edu-note" id="fsf-licensing" role="complementary">
106    <p style="font-size:80%">
107    Have a question about free software licensing not answered here?
108    See our other <a href="http://www.fsf.org/licensing">licensing resources</a>,
109    and if necessary contact the FSF Compliance Lab
110    at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p>
111    <hr class="no-display" />
112    </div>
113    
114    
115    <h3 id="fs-definition">The Free Software Definition</h3>
116    
117    <p>
118    The free software definition presents the criteria for whether a
119    particular software program qualifies as free software.  From time to
120    time we revise this definition, to clarify it or to resolve questions
121    about subtle issues.  See the <a href="#History">History section</a>
122    below for a list of changes that affect the definition of free
123    software.
124  </p>  </p>
125    
126    <h4 id="four-freedoms">The four essential freedoms</h4>
127  <p>  <p>
128  A program is free software if the program's users have the  A program is free software if the program's users have the
129  four essential freedoms:  four essential freedoms: <a href="#f1">[1]</a>
130  </p>  </p>
131    
132  <ul>  <ul class="important">
133    <li>The freedom to run the program, for any purpose (freedom 0).</li>    <li>The freedom to run the program as you wish,
134          for any purpose (freedom 0).</li>
135    <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
136        does your computing as you wish (freedom 1). Access to the source        does your computing as you wish (freedom 1). Access to the source
137        code is a precondition for this.        code is a precondition for this.
138    </li>    </li>
139    <li>The freedom to redistribute copies so you can help your neighbor    <li>The freedom to redistribute copies so you can help others
140        (freedom 2).        (freedom 2).
141    </li>    </li>
142    <li>The freedom to distribute copies of your modified versions    <li>The freedom to distribute copies of your modified versions
# Line 68  four essential freedoms: Line 147  four essential freedoms:
147  </ul>  </ul>
148    
149  <p>  <p>
150  A program is free software if users have all of these freedoms.  Thus,  A program is free software if it gives users adequately all of these
151  you should be free to redistribute copies, either with or without  freedoms.  Otherwise, it is nonfree.  While we can distinguish various
152  modifications, either gratis or charging a fee for distribution, to  nonfree distribution schemes in terms of how far they fall short of
153  <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these  being free, we consider them all equally unethical.</p>
154  things means (among other things) that you do not have to ask or pay  
155  for permission to do so.  <p>In any given scenario, these freedoms must apply to whatever code
156    we plan to make use of, or lead others to make use of.  For instance,
157    consider a program A which automatically launches a program B to
158    handle some cases.  If we plan to distribute A as it stands, that
159    implies users will need B, so we need to judge whether both A and B
160    are free.  However, if we plan to modify A so that it doesn't use B,
161    only A needs to be free; B is not pertinent to that plan.</p>
162    
163    
164    <h4 id="selling">Free software <em>can</em> be commercial</h4>
165    
166    <p>
167    &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial.&rdquo;
168    On the contrary, a free program must be available for commercial use,
169    commercial development, and commercial distribution.  This policy is
170    of fundamental importance&mdash;without this, free software could not
171    achieve its aims.
172  </p>  </p>
173    
174  <p>  <p>
175  You should also have the freedom to make modifications and use them  We want to invite everyone to use the GNU system, including businesses
176  privately in your own work or play, without even mentioning that they  and their workers.  That requires allowing commercial use.  We hope
177  exist.  If you do publish your changes, you should not be required to  that free replacement programs will supplant comparable proprietary
178  notify anyone in particular, or in any particular way.  programs, but they can't do that if businesses are forbidden to use
179    them.  We want commercial products that contain software to include
180    the GNU system, and that would constitute commercial distribution for
181    a price.  Commercial development of free software is no longer
182    unusual; such free commercial software is very important.  Paid,
183    professional support for free software fills an important need.
184    </p>
185    
186    <p>
187    Thus, to exclude commercial use, commercial development or commercial
188    distribution would hobble the free software community and obstruct its
189    path to success.  We must conclude that a program licensed with such
190    restrictions does not qualify as free software.
191    </p>
192    
193    <p>
194    A free program must offer the four freedoms to any would-be user that
195    obtains a copy of the software, who has complied thus far with the
196    conditions of the free license covering the software in any previous
197    distribution of it.  Putting some of the freedoms off limits to some
198    users, or requiring that users pay, in money or in kind, to exercise
199    them, is tantamount to not granting the freedoms in question, and thus
200    renders the program nonfree.
201  </p>  </p>
202    
203    
204    <h3 id="clarifying">Clarifying the Boundary Between Free and Nonfree</h3>
205    
206    <p>In the rest of this article we explain more precisely how far the
207    various freedoms need to extend, on various issues, in order for a
208    program to be free.</p>
209    
210    <h4 id="run-the-program">The freedom to run the program as you wish</h4>
211    
212  <p>  <p>
213  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
214  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 95  for her purposes, but you are not entitl Line 221  for her purposes, but you are not entitl
221  </p>  </p>
222    
223  <p>  <p>
224  The freedom to redistribute copies must include binary or executable  The freedom to run the program as you wish means that you are not
225  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
226  unmodified versions.  (Distributing programs in runnable form is necessary  functionality the program has, whether it is technically capable of
227  for conveniently installable free operating systems.)  It is OK if there  functioning in any given environment, or whether it is useful for any
228  is no way to produce a binary or executable form for a certain program  particular computing activity.</p>
229  (since some languages don't support that feature), but you must have the  
230  freedom to redistribute such forms should you find or develop a way to  <p>For example, if the code arbitrarily rejects certain meaningful
231  make them.  inputs&mdash;or even fails unconditionally&mdash;that may make the
232  </p>  program less useful, perhaps even totally useless, but it does not
233    deny users the freedom to run the program, so it does not conflict
234    with freedom 0.  If the program is free, the users can overcome the
235    loss of usefulness, because freedoms 1 and 3 permit users and
236    communities to make and distribute modified versions without the
237    arbitrary nuisance code.</p>
238    
239    <p>&ldquo;As you wish&rdquo; includes, optionally, &ldquo;not at
240    all&rdquo; if that is what you wish.  So there is no need for a
241    separate &ldquo;freedom not to run a program.&rdquo;</p>
242    
243    <h4 id="make-changes">The freedom to study the source code and make changes</h4>
244    
245  <p>  <p>
246  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
247  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
248  access to the source code of the program.  Therefore, accessibility of  access to the source code of the program.  Therefore, accessibility of
249  source code is a necessary condition for free software.  Obfuscated  source code is a necessary condition for free software.  Obfuscated
250  &ldquo;source code&rdquo; is not real source code and does not count  &ldquo;source code&rdquo; is not real source code and does not count
# Line 117  as source code. Line 254  as source code.
254  <p>  <p>
255  Freedom 1 includes the freedom to use your changed version in place of  Freedom 1 includes the freedom to use your changed version in place of
256  the original.  If the program is delivered in a product designed to  the original.  If the program is delivered in a product designed to
257  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
258  practice known as &ldquo;tivoization&rdquo; or &ldquo;lockdown&rdquo;,  practice known as &ldquo;tivoization&rdquo; or &ldquo;lockdown,&rdquo;
259  or (in its practitioners' perverse terminology) as &ldquo;secure  or (in its practitioners' perverse terminology) as &ldquo;secure
260  boot&rdquo; &mdash; freedom 1 becomes a theoretical fiction rather  boot&rdquo;&mdash;freedom 1 becomes an empty pretense rather than a
261  than a practical freedom.  This is not sufficient.  In other words,  practical reality.  These binaries are not free
262  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.  
263  </p>  </p>
264    
265  <p>  <p>
266  One important way to modify a program is by merging in available free  One important way to modify a program is by merging in available free
267  subroutines and modules.  If the program's license says that you  subroutines and modules.  If the program's license says that you
268  cannot merge in a suitably licensed existing module &mdash; for instance, if it  cannot merge in a suitably licensed existing module&mdash;for instance, if it
269  requires you to be the copyright holder of any code you add &mdash; then the  requires you to be the copyright holder of any code you add&mdash;then the
270  license is too restrictive to qualify as free.  license is too restrictive to qualify as free.
271  </p>  </p>
272    
273  <p>  <p>
274    Whether a change constitutes an improvement is a subjective matter.
275    If your right to modify a program is limited, in substance, to changes that
276    someone else considers an improvement, that program is not free.
277    </p>
278    
279    <p>
280    One special case of freedom 1 is to delete the program's code so it
281    returns after doing nothing, or make it invoke some other program.
282    Thus, freedom 1 includes the &ldquo;freedom to delete the program.&rdquo;
283    </p>
284    
285    <h4 id="redistribute">The freedom to redistribute if you wish: basic
286    requirements</h4>
287    
288    <p>Freedom to distribute (freedoms 2 and 3) means you are free to
289    redistribute copies, either with or without modifications, either
290    gratis or charging a fee for distribution, to
291    <a href="#exportcontrol">anyone anywhere</a>.  Being free to do these
292    things means (among other things) that you do not have to ask or pay
293    for permission to do so.
294    </p>
295    
296    <p>
297    You should also have the freedom to make modifications and use them
298    privately in your own work or play, without even mentioning that they
299    exist.  If you do publish your changes, you should not be required to
300    notify anyone in particular, or in any particular way.
301    </p>
302    
303    <p>
304  Freedom 3 includes the freedom to release your modified versions  Freedom 3 includes the freedom to release your modified versions
305  as free software.  A free license may also permit other ways of  as free software.  A free license may also permit other ways of
306  releasing them; in other words, it does not have to be  releasing them; in other words, it does not have to be
307  a <a href="/copyleft/copyleft.html">copyleft</a> license.  However, a  a <a href="/licenses/copyleft.html">copyleft</a> license.  However, a
308  license that requires modified versions to be nonfree does not qualify  license that requires modified versions to be nonfree does not qualify
309  as a free license.  as a free license.
310  </p>  </p>
311    
312  <p>  <p>
313  In order for these freedoms to be real, they must be permanent and  The freedom to redistribute copies must include binary or executable
314  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
315  software has the power to revoke the license, or retroactively add  unmodified versions.  (Distributing programs in runnable form is necessary
316  restrictions to its terms, without your doing anything wrong to give  for conveniently installable free operating systems.)  It is OK if there
317  cause, the software is not free.  is no way to produce a binary or executable form for a certain program
318    (since some languages don't support that feature), but you must have the
319    freedom to redistribute such forms should you find or develop a way to
320    make them.
321  </p>  </p>
322    
323    <h4 id="copyleft">Copyleft</h4>
324    
325  <p>  <p>
326  However, certain kinds of rules about the manner of distributing free  Certain kinds of rules about the manner of distributing free
327  software are acceptable, when they don't conflict with the central  software are acceptable, when they don't conflict with the central
328  freedoms.  For example, copyleft (very simply stated) is the rule that  freedoms.  For example, <a href="/licenses/copyleft.html">copyleft</a>
329  when redistributing the program, you cannot add restrictions to deny  (very simply stated) is the rule that when redistributing the program,
330  other people the central freedoms.  This rule does not conflict with  you cannot add restrictions to deny other people the central freedoms.
331  the central freedoms; rather it protects them.  This rule does not conflict with the central freedoms; rather it
332    protects them.
333  </p>  </p>
334    
335  <p>  <p>
336  &ldquo;Free software&rdquo; does not mean &ldquo;noncommercial&rdquo;.  A free  In the GNU project, we use copyleft to protect the four freedoms
337  program must be available for commercial use, commercial development,  legally for everyone.  We believe there are important reasons why
338  and commercial distribution.  Commercial development of free software  <a href="/philosophy/pragmatic.html">it is better to use
339  is no longer unusual; such free commercial software is very important.  copyleft</a>.  However,
340  You may have paid money to get copies of free software, or you may have  <a href="/philosophy/categories.html#Non-CopyleftedFreeSoftware">
341  obtained copies at no charge.  But regardless of how you got your copies,  noncopylefted free software</a> is ethical
342  you always have the freedom to copy and change the software, even to  too.  See <a href="/philosophy/categories.html">Categories of Free
343  <a href="/philosophy/selling.html">sell copies</a>.  Software</a> for a description of how &ldquo;free software,&rdquo;
344    &ldquo;copylefted software&rdquo; and other categories of software
345    relate to each other.
346  </p>  </p>
347    
348  <p>  <h4 id="packaging">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>  
349    
350  <p>  <p>
351  However, rules about how to package a modified version are acceptable,  Rules about how to package a modified version are acceptable,
352  if they don't substantively limit your freedom to release modified  if they don't substantively limit your freedom to release modified
353  versions, or your freedom to make and use modified versions privately.  versions, or your freedom to make and use modified versions privately.
354  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 190  the program, so you won't have trouble m Line 360  the program, so you won't have trouble m
360  </p>  </p>
361    
362  <p>  <p>
 A special issue arises when a license requires changing the name by  
 which the program will be invoked from other programs.  That  
 effectively hampers you from releasing your changed version so that it  
 can replace the original when invoked by those other programs.  This  
 sort of requirement is acceptable only if there's a suitable aliasing  
 facility that allows you to specify the original program's name as an  
 alias for the modified version.</p>  
   
 <p>  
363  Rules that &ldquo;if you make your version available in this way, you  Rules that &ldquo;if you make your version available in this way, you
364  must make it available in that way also&rdquo; can be acceptable too,  must make it available in that way also&rdquo; can be acceptable too,
365  on the same condition.  An example of such an acceptable rule is one  on the same condition.  An example of such an acceptable rule is one
# Line 211  are also acceptable. Line 372  are also acceptable.
372  </p>  </p>
373    
374  <p>  <p>
375  In the GNU project, we use  A special issue arises when a license requires changing the name by
376  <a href="/copyleft/copyleft.html">copyleft</a>  which the program will be invoked from other programs.  That
377  to protect these freedoms legally for everyone.  But  effectively hampers you from releasing your changed version so that it
378  <a href="/philosophy/categories.html#Non-CopyleftedFreeSoftware">noncopylefted  can replace the original when invoked by those other programs.  This
379  free software</a> also exists.  We believe there are important reasons why  sort of requirement is acceptable only if there's a suitable aliasing
380  <a href="/philosophy/pragmatic.html">it is better to use copyleft</a>,  facility that allows you to specify the original program's name as an
381  but if your program is noncopylefted free software, it is still basically  alias for the modified version.</p>
382  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.)  
383  </p>  <h4 id="exportcontrol">Export regulations</h4>
384    
385  <p>  <p>
386  Sometimes government <a id="exportcontrol">export control regulations</a>  Sometimes government export control regulations
387  and trade sanctions can constrain your freedom to distribute copies of  and trade sanctions can constrain your freedom to distribute copies of
388  programs internationally.  Software developers do not have the power to  programs internationally.  Software developers do not have the power to
389  eliminate or override these restrictions, but what they can and must do  eliminate or override these restrictions, but what they can and must do
390  is refuse to impose them as conditions of use of the program.  In this  is refuse to impose them as conditions of use of the program.  In this
391  way, the restrictions will not affect activities and people outside the  way, the restrictions will not affect activities and people outside the
392  jurisdictions of these governments.  Thus, free software licenses  jurisdictions of these governments.  Thus, free software licenses
393  must not require obedience to any export regulations as a condition of  must not require obedience to any nontrivial export regulations as a
394  any of the essential freedoms.  condition of exercising any of the essential freedoms.
395    </p>
396    
397    <p>
398    Merely mentioning the existence of export regulations, without making
399    them a condition of the license itself, is acceptable since it does
400    not restrict users.  If an export regulation is actually trivial for
401    free software, then requiring it as a condition is not an actual
402    problem; however, it is a potential problem, since a later change in
403    export law could make the requirement nontrivial and thus render the
404    software nonfree.
405    </p>
406    
407    <h4 id="legal-details">Legal considerations</h4>
408    
409    <p>
410    In order for these freedoms to be real, they must be permanent and
411    irrevocable as long as you do nothing wrong; if the developer of the
412    software has the power to revoke the license, or retroactively add
413    restrictions to its terms, without your doing anything wrong to give
414    cause, the software is not free.
415    </p>
416    
417    <p>
418    A free license may not require compliance with the license of a
419    nonfree program.  Thus, for instance, if a license requires you to
420    comply with the licenses of &ldquo;all the programs you use,&rdquo; in
421    the case of a user that runs nonfree programs this would require
422    compliance with the licenses of those nonfree programs; that makes the
423    license nonfree.
424  </p>  </p>
425    
426  <p>  <p>
427    It is acceptable for a free license to specify which jurisdiction's
428    law applies, or where litigation must be done, or both.
429    </p>
430    
431    <h4 id="contracts">Contract-based licenses</h4>
432    
433    <p>
434  Most free software licenses are based on copyright, and there are limits  Most free software licenses are based on copyright, and there are limits
435  on what kinds of requirements can be imposed through copyright.  If a  on what kinds of requirements can be imposed through copyright.  If a
436  copyright-based license respects freedom in the ways described above, it  copyright-based license respects freedom in the ways described above, it
# Line 252  legitimate, we will have to think about Line 449  legitimate, we will have to think about
449  it is nonfree.  it is nonfree.
450  </p>  </p>
451    
452  <p>  <h3 id="in-practice">The Free Software Definition in Practice</h3>
453  When talking about free software, it is best to avoid using terms  
454  like &ldquo;give away&rdquo; or &ldquo;for free,&rdquo; because those terms imply that  <h4 id="interpretation">How we interpret these criteria</h4>
 the issue is about price, not freedom.  Some common terms such  
 as &ldquo;piracy&rdquo; embody opinions we hope you won't endorse.  See  
 <a href="/philosophy/words-to-avoid.html">Confusing Words and Phrases that  
 are Worth Avoiding</a> for a discussion of these terms.  We also have  
 a list of proper <a href="/philosophy/fs-translations.html">translations of  
 &ldquo;free software&rdquo;</a> into various languages.  
 </p>  
455    
456  <p>  <p>
457  Finally, note that criteria such as those stated in this free software  Note that criteria such as those stated in this free software
458  definition require careful thought for their interpretation.  To decide  definition require careful thought for their interpretation.  To decide
459  whether a specific software license qualifies as a free software license,  whether a specific software license qualifies as a free software license,
460  we judge it based on these criteria to determine whether it fits their  we judge it based on these criteria to determine whether it fits their
# Line 277  a conclusion about a new issue, we often Line 467  a conclusion about a new issue, we often
467  it easier to see why certain licenses do or don't qualify.  it easier to see why certain licenses do or don't qualify.
468  </p>  </p>
469    
470    <h4 id="get-help">Get help with free licenses</h4>
471    
472  <p>  <p>
473  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
474  software license, see our <a href="/licenses/license-list.html">list  software license, see our <a href="/licenses/license-list.html">list
# Line 299  help you can ensure that the license rea Line 491  help you can ensure that the license rea
491  and avoid various practical problems.  and avoid various practical problems.
492  </p>  </p>
493    
494    <h4 id="terminology">Use the right words when talking about free software</h4>
495    
496    <p>
497    When talking about free software, it is best to avoid using terms
498    like &ldquo;give away&rdquo; or &ldquo;for free,&rdquo; because those terms imply that
499    the issue is about price, not freedom.  Some common terms such
500    as &ldquo;piracy&rdquo; embody opinions we hope you won't endorse.  See
501    <a href="/philosophy/words-to-avoid.html">Confusing Words and Phrases that
502    are Worth Avoiding</a> for a discussion of these terms.  We also have
503    a list of proper <a href="/philosophy/fs-translations.html">translations of
504    &ldquo;free software&rdquo;</a> into various languages.
505    </p>
506    
507    <p id="open-source">
508    Another group uses the term &ldquo;open source&rdquo; to mean
509    something close (but not identical) to &ldquo;free software.&rdquo;  We
510    prefer the term &ldquo;free software&rdquo; because, once you have heard that
511    it refers to freedom rather than price, it calls to mind freedom.  The
512    word &ldquo;open&rdquo; never refers to freedom.
513    </p>
514    
515  <h3 id="beyond-software">Beyond Software</h3>  <h3 id="beyond-software">Beyond Software</h3>
516    
517  <p>  <p>
# Line 309  manuals are in effect part of the softwa Line 522  manuals are in effect part of the softwa
522    
523  <p>  <p>
524  The same arguments also make sense for other kinds of works of  The same arguments also make sense for other kinds of works of
525  practical use &mdash; that is to say, works that embody useful knowledge,  practical use&mdash;that is to say, works that embody useful knowledge,
526  such as educational works and reference  such as educational works and reference
527  works.  <a href="http://wikipedia.org">Wikipedia</a> is the best-known  works.  <a href="https://wikipedia.org">Wikipedia</a> is the best-known
528  example.  example.
529  </p>  </p>
530    
# Line 321  has been extended to a definition of <a Line 534  has been extended to a definition of <a
534  free cultural works</a> applicable to any kind of works.  free cultural works</a> applicable to any kind of works.
535  </p>  </p>
536    
 <h3 id="open-source">Open Source?</h3>  
   
 <p>  
 Another group has started using 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>  
   
537  <h3 id="History">History</h3>  <h3 id="History">History</h3>
538    
539  <p>From time to time we revise this Free Software Definition.  Here is  <p>From time to time we revise this Free Software Definition.  Here is
540  the list of changes, along with links to show exactly what was  the list of substantive changes, along with links to show exactly what
541  changed.</p>  was changed.</p>
542    
543  <ul>  <ul>
544    
545  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.110&amp;r2=1.111">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.168&amp;r2=1.169">Version
546    1.169</a>: Explain more clearly why the four freedoms must apply
547    to commercial activity.  Explain why the four freedoms imply the
548    freedom not to run the program and the freedom to delete it, so there
549    is no need to state those as separate requirements.</li>
550    
551    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.164&amp;r2=1.165">Version
552    1.165</a>: Clarify that arbitrary annoyances in the code do not
553    negate freedom 0, and that freedoms 1 and 3 enable users to remove them.</li>
554    
555    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.152&amp;r2=1.153">Version
556    1.153</a>: Clarify that freedom to run the program means nothing stops
557    you from making it run.</li>
558    
559    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.140&amp;r2=1.141">Version
560    1.141</a>: Clarify which code needs to be free.</li>
561    
562    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.134&amp;r2=1.135">Version
563    1.135</a>: Say each time that freedom 0 is the freedom to run the program
564    as you wish.</li>
565    
566    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.133&amp;r2=1.134">Version
567    1.134</a>: Freedom 0 is not a matter of the program's functionality.</li>
568    
569    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.130&amp;r2=1.131">Version
570    1.131</a>: A free license may not require compliance with a nonfree license
571    of another program.</li>
572    
573    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.128&amp;r2=1.129">Version
574    1.129</a>: State explicitly that choice of law and choice of forum
575    specifications are allowed.  (This was always our policy.)</li>
576    
577    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.121&amp;r2=1.122">Version
578    1.122</a>: An export control requirement is a real problem if the
579    requirement is nontrivial; otherwise it is only a potential problem.</li>
580    
581    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.117&amp;r2=1.118">Version
582    1.118</a>: Clarification: the issue is limits on your right to modify,
583    not on what modifications you have made.  And modifications are not limited
584    to &ldquo;improvements&rdquo;</li>
585    
586    <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.110&amp;r2=1.111">Version
587  1.111</a>: Clarify 1.77 by saying that only  1.111</a>: Clarify 1.77 by saying that only
588  retroactive <em>restrictions</em> are unacceptable.  The copyright  retroactive <em>restrictions</em> are unacceptable.  The copyright
589  holders can always grant additional <em>permission</em> for use of the  holders can always grant additional <em>permission</em> for use of the
590  work by releasing the work in another way in parallel.</li>  work by releasing the work in another way in parallel.</li>
591    
592  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.104&amp;r2=1.105">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.104&amp;r2=1.105">Version
593  1.105</a>: Reflect, in the brief statement of freedom 1, the point  1.105</a>: Reflect, in the brief statement of freedom 1, the point
594  (already stated in version 1.80) that it includes really using your modified  (already stated in version 1.80) that it includes really using your modified
595  version for your computing.</li>  version for your computing.</li>
596    
597  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.91&amp;r2=1.92">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.91&amp;r2=1.92">Version
598  1.92</a>: Clarify that obfuscated code does not qualify as source code.</li>  1.92</a>: Clarify that obfuscated code does not qualify as source code.</li>
599    
600  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.89&amp;r2=1.90">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.89&amp;r2=1.90">Version
601  1.90</a>: Clarify that freedom 3 means the right to distribute copies  1.90</a>: Clarify that freedom 3 means the right to distribute copies
602  of your own modified or improved version, not a right to participate  of your own modified or improved version, not a right to participate
603  in someone else's development project.</li>  in someone else's development project.</li>
604    
605  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.88&amp;r2=1.89">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.88&amp;r2=1.89">Version
606  1.89</a>: Freedom 3 includes the right to release modified versions as  1.89</a>: Freedom 3 includes the right to release modified versions as
607  free software.</li>  free software.</li>
608    
609  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.79&amp;r2=1.80">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.79&amp;r2=1.80">Version
610  1.80</a>: Freedom 1 must be practical, not just theoretical;  1.80</a>: Freedom 1 must be practical, not just theoretical;
611  i.e., no tivoization.</li>  i.e., no tivoization.</li>
612    
613  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.76&amp;r2=1.77">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.76&amp;r2=1.77">Version
614  1.77</a>: Clarify that all retroactive changes to the license are  1.77</a>: Clarify that all retroactive changes to the license are
615  unacceptable, even if it's not described as a complete  unacceptable, even if it's not described as a complete
616  replacement.</li>  replacement.</li>
617    
618  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.73&amp;r2=1.74">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.73&amp;r2=1.74">Version
619  1.74</a>: Four clarifications of points not explicit enough, or stated  1.74</a>: Four clarifications of points not explicit enough, or stated
620  in some places but not reflected everywhere:  in some places but not reflected everywhere:
621  <ul>  <ul>
# Line 386  refers to those that are suitably licens Line 629  refers to those that are suitably licens
629  </ul>  </ul>
630  </li>  </li>
631    
632  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.56&amp;r2=1.57">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.56&amp;r2=1.57">Version
633  1.57</a>: Add &quot;Beyond Software&quot; section.</li>  1.57</a>: Add &quot;Beyond Software&quot; section.</li>
634    
635  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.45&amp;r2=1.46">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.45&amp;r2=1.46">Version
636  1.46</a>: Clarify whose purpose is significant in the freedom to run  1.46</a>: Clarify whose purpose is significant in the freedom to run
637  the program for any purpose.</li>  the program for any purpose.</li>
638    
639  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.40&amp;r2=1.41">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.40&amp;r2=1.41">Version
640  1.41</a>: Clarify wording about contract-based licenses.</li>  1.41</a>: Clarify wording about contract-based licenses.</li>
641    
642  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.39&amp;r2=1.40">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.39&amp;r2=1.40">Version
643  1.40</a>: Explain that a free license must allow to you use other  1.40</a>: Explain that a free license must allow to you use other
644  available free software to create your modifications.</li>  available free software to create your modifications.</li>
645    
646  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.38&amp;r2=1.39">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.38&amp;r2=1.39">Version
647  1.39</a>: Note that it is acceptable for a license to require you to  1.39</a>: Note that it is acceptable for a license to require you to
648  provide source for versions of the software you put into public  provide source for versions of the software you put into public
649  use.</li>  use.</li>
650    
651  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.30&amp;r2=1.31">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.30&amp;r2=1.31">Version
652  1.31</a>: Note that it is acceptable for a license to require you to  1.31</a>: Note that it is acceptable for a license to require you to
653  identify yourself as the author of modifications.  Other minor  identify yourself as the author of modifications.  Other minor
654  clarifications throughout the text.</li>  clarifications throughout the text.</li>
655    
656  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.22&amp;r2=1.23">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.22&amp;r2=1.23">Version
657  1.23</a>: Address potential problems related to contract-based  1.23</a>: Address potential problems related to contract-based
658  licenses.</li>  licenses.</li>
659    
660  <li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.15&amp;r2=1.16">Version  <li><a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.15&amp;r2=1.16">Version
661  1.16</a>: Explain why distribution of binaries is important.</li>  1.16</a>: Explain why distribution of binaries is important.</li>
662    
663  <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="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;r1=1.10&amp;r2=1.11">Version
664  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
665  versions you distribute to the author.</li>  versions you distribute to previous developers on request.</li>
666    
667  </ul>  </ul>
668    
669  <p>There are gaps in the version numbers shown above because there are  <p>There are gaps in the version numbers shown above because there are
670  other changes in this page that do not affect the definition as such.  other changes in this page that do not affect the definition or its
671  These changes are in other parts of the page.  You can review the  interpretations.  For instance, the list does not include changes in
672  complete list of changes to the page through  asides, formatting, spelling, punctuation, or other parts of the page.
673  the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;view=log">cvsweb  You can review the complete list of changes to the page through
674    the <a href="//web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&amp;view=log">cvsweb
675  interface</a>.</p>  interface</a>.</p>
676    <div class="column-limit"></div>
677    
678    <h3 class="footnote">Footnote</h3>
679    <ol>
680    <li id="f1">The reason they are numbered 0, 1, 2 and 3 is historical. Around
681    1990 there were three freedoms, numbered 1, 2 and 3. Then we realized that
682    the freedom to run the program needed to be mentioned explicitly.
683    It was clearly more basic than the other three, so it properly should
684    precede them. Rather than renumber the others, we made it freedom&nbsp;0.</li>
685    </ol>
686  </div>  </div>
687    
688    </div><!-- for id="content", starts in the include above -->
689  <!--#include virtual="/server/footer.html" -->  <!--#include virtual="/server/footer.html" -->
690    <div id="footer" role="contentinfo">
691    <div class="unprintable">
692    
693  <div id="footer">  <p>Please send general FSF &amp; GNU inquiries to
   
 <p>  
 Please send FSF &amp; GNU inquiries to  
694  <a href="mailto:gnu@gnu.org">&lt;gnu@gnu.org&gt;</a>.  <a href="mailto:gnu@gnu.org">&lt;gnu@gnu.org&gt;</a>.
695  There are also <a href="/contact/">other ways to contact</a>  There are also <a href="/contact/">other ways to contact</a>
696  the FSF.  the FSF.  Broken links and other corrections or suggestions can be sent
697  <br />  to <a href="mailto:webmasters@gnu.org">&lt;webmasters@gnu.org&gt;</a>.</p>
698  Please send broken links and other corrections or suggestions to  
699  <a href="mailto:webmasters@gnu.org">&lt;webmasters@gnu.org&gt;</a>.  <p><!-- TRANSLATORS: Ignore the original text in this paragraph,
700  </p>          replace it with the translation of these two:
701    
702            We work hard and do our best to provide accurate, good quality
703            translations.  However, we are not exempt from imperfection.
704            Please send your comments and general suggestions in this regard
705            to <a href="mailto:web-translators@gnu.org">
706            &lt;web-translators@gnu.org&gt;</a>.</p>
707    
708            <p>For information on coordinating and contributing translations of
709            our web pages, see <a
710            href="/server/standards/README.translations.html">Translations
711            README</a>. -->
712    Please see the <a
713    href="/server/standards/README.translations.html">Translations
714    README</a> for information on coordinating and contributing translations
715    of this article.</p>
716    </div>
717    
718  <p>  <!-- Regarding copyright, in general, standalone pages (as opposed to
719  Please see the       files generated as part of manuals) on the GNU web server should
720  <a href="/server/standards/README.translations.html">Translations       be under CC BY-ND 4.0.  Please do NOT change or remove this
721  README</a> for information on coordinating and submitting       without talking with the webmasters or licensing team first.
722  translations of this article.       Please make sure the copyright date is consistent with the
723  </p>       document.  For web pages, it is ok to list just the latest year the
724         document was modified, or published.
725        
726         If you wish to list earlier years, that is ok too.
727         Either "2001, 2002, 2003" or "2001-2003" are ok for specifying
728         years, as long as each year in the range is in fact a copyrightable
729         year, i.e., a year in which the document was published (including
730         being publicly visible on the web or in a revision control system).
731        
732         There is more detail about copyright years in the GNU Maintainers
733         Information document, www.gnu.org/prep/maintain. -->
734    
735    <p>Copyright &copy; 1996-2002, 2004-2019, 2021
736    Free Software Foundation, Inc.</p>
737    
 <p>  
 Copyright &copy; 1996-2002, 2004-2007, 2009, 2010, 2012 Free Software  
 Foundation, Inc.  
 </p>  
738  <p>This page is licensed under a <a rel="license"  <p>This page is licensed under a <a rel="license"
739  href="http://creativecommons.org/licenses/by-nd/3.0/us/">Creative  href="http://creativecommons.org/licenses/by-nd/4.0/">Creative
740  Commons Attribution-NoDerivs 3.0 United States License</a>.  Commons Attribution-NoDerivatives 4.0 International License</a>.</p>
 </p>  
741    
742  <!--#include virtual="/server/bottom-notes.html" -->  <!--#include virtual="/server/bottom-notes.html" -->
743    
744  <p>Updated:  <p class="unprintable">Updated:
745  <!-- timestamp start -->  <!-- timestamp start -->
746  $Date$  $Date$
747  <!-- timestamp end -->  <!-- timestamp end -->
748  </p>  </p>
749  </div>  </div>
750    </div><!-- for class="inner", starts in the banner include -->
   
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751  </body>  </body>
752  </html>  </html>

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