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<title>What is free software? - GNU Project - Free Software Foundation (FSF)</title> |
<title>What is free software? |
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- GNU Project - Free Software Foundation</title> |
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<h2>What is free software?</h2> |
<h2>What is free software?</h2> |
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<p> |
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“Free software” means software that respects users' |
“Free software” means software that respects users' |
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freedom and community. Roughly, <b>the users have the freedom to run, |
freedom and community. Roughly, <b>the users have the freedom to run, |
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copy, distribute, study, change and improve the software</b>. With these |
copy, distribute, study, change and improve the software</b>. |
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freedoms, the users (both individually and collectively) control the |
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program and what it does for them. |
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When users don't control the program, the program controls the users. |
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The developer controls the program, and through it controls the users. |
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This nonfree or “proprietary” program is therefore an |
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instrument of unjust power. |
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With these freedoms, the users (both individually and collectively) |
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control the program and what it does for them. When users don't |
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control the program, the program controls the users. The developer |
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controls the program, and through it exercises power over the users. |
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Therefore, a “nonfree” or “proprietary” program |
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is <a href="/philosophy/free-software-even-more-important.html"> an |
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instrument of unjust power</a>. |
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</p> |
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A program is free software if the program's users have the |
A program is free software if the program's users have the |
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four essential freedoms: |
four essential freedoms: |
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</p> |
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</ul> |
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<p> |
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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 |
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you should be free to redistribute copies, either with or without |
freedoms. Otherwise, it is nonfree. While we can distinguish various |
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modifications, either gratis or charging a fee for distribution, to |
nonfree distribution schemes in terms of how far they fall short of |
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being free, we consider them all equally unethical.</p> |
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<p>The rest of this page clarifies certain points about what makes |
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specific freedoms adequate or not.</p> |
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<p>Freedom to distribute (freedoms 2 and 3) means you are free to |
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redistribute copies, either with or without modifications, either |
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gratis or charging a fee for distribution, to |
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<a href="#exportcontrol">anyone anywhere</a>. Being free to do these |
<a href="#exportcontrol">anyone anywhere</a>. Being free to do these |
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things means (among other things) that you do not have to ask or pay |
things means (among other things) that you do not have to ask or pay |
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for permission to do so. |
for permission to do so. |
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<p> |
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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 |
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freedom to publish improved versions) to be meaningful, you must have |
freedom to publish the changed versions) to be meaningful, you must have |
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access to the source code of the program. Therefore, accessibility of |
access to the source code of the program. Therefore, accessibility of |
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source code is a necessary condition for free software. Obfuscated |
source code is a necessary condition for free software. Obfuscated |
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“source code” is not real source code and does not count |
“source code” is not real source code and does not count |
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<p> |
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Whether a change constitutes an improvement is a subjective matter. |
Whether a change constitutes an improvement is a subjective matter. |
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If your modifications are limited, in substance, to changes that |
If your right to modify a program is limited, in substance, to changes that |
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someone else considers an improvement, that is not freedom. |
someone else considers an improvement, that program is not free. |
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</p> |
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<p> |
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A special issue arises when a license requires changing the name by |
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which the program will be invoked from other programs. That |
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effectively hampers you from releasing your changed version so that it |
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can replace the original when invoked by those other programs. This |
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sort of requirement is acceptable only if there's a suitable aliasing |
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facility that allows you to specify the original program's name as an |
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alias for the modified version.</p> |
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<p> |
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Rules that “if you make your version available in this way, you |
Rules that “if you make your version available in this way, you |
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must make it available in that way also” can be acceptable too, |
must make it available in that way also” can be acceptable too, |
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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 |
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</p> |
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<p> |
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A special issue arises when a license requires changing the name by |
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which the program will be invoked from other programs. That |
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effectively hampers you from releasing your changed version so that it |
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can replace the original when invoked by those other programs. This |
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sort of requirement is acceptable only if there's a suitable aliasing |
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facility that allows you to specify the original program's name as an |
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alias for the modified version.</p> |
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<p> |
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In the GNU project, we use |
In the GNU project, we use |
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<a href="/copyleft/copyleft.html">copyleft</a> |
<a href="/copyleft/copyleft.html">copyleft</a> |
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to protect these freedoms legally for everyone. But |
to protect these freedoms legally for everyone. But |
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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 |
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way, the restrictions will not affect activities and people outside the |
way, the restrictions will not affect activities and people outside the |
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jurisdictions of these governments. Thus, free software licenses |
jurisdictions of these governments. Thus, free software licenses |
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must not require obedience to any export regulations as a condition of |
must not require obedience to any nontrivial export regulations as a |
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any of the essential freedoms. |
condition of exercising any of the essential freedoms. |
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</p> |
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<p> |
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Merely mentioning the existence of export regulations, without making |
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them a condition of the license itself, is acceptable since it does |
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not restrict users. If an export regulation is actually trivial for |
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free software, then requiring it as a condition is not an actual |
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problem; however, it is a potential problem, since a later change in |
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export law could make the requirement nontrivial and thus render the |
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software nonfree. |
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</p> |
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<p> |
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and avoid various practical problems. |
and avoid various practical problems. |
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</p> |
</p> |
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<h2 id="beyond-software">Beyond Software</h2> |
<h3 id="beyond-software">Beyond Software</h3> |
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<p> |
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<a href="/philosophy/free-doc.html">Software manuals must be free</a>, |
<a href="/philosophy/free-doc.html">Software manuals must be free</a>, |
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free cultural works</a> applicable to any kind of works. |
free cultural works</a> applicable to any kind of works. |
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</p> |
</p> |
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<h2 id="open-source">Open Source?</h2> |
<h3 id="open-source">Open Source?</h3> |
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<p> |
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Another group has started using the term “open source” to mean |
Another group has started using the term “open source” to mean |
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never refers to freedom</a>. |
never refers to freedom</a>. |
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</p> |
</p> |
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<h2 id="History">History</h2> |
<h3 id="History">History</h3> |
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<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 |
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the list of changes, along with links to show exactly what was |
the list of substantive changes, along with links to show exactly what |
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changed.</p> |
was changed.</p> |
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<ul> |
<ul> |
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<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.121&r2=1.122">Version |
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1.122</a>: An export control requirement is a real problem if the |
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requirement is nontrivial; otherwise it is only a potential problem.</li> |
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<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.117&r2=1.118">Version |
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1.118</a>: Clarification: the issue is limits on your right to modify, |
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not on what modifications you have made. And modifications are not limited |
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to “improvements”</li> |
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<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.110&r2=1.111">Version |
<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.110&r2=1.111">Version |
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1.111</a>: Clarify 1.77 by saying that only |
1.111</a>: Clarify 1.77 by saying that only |
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retroactive <em>restrictions</em> are unacceptable. The copyright |
retroactive <em>restrictions</em> are unacceptable. The copyright |
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</ul> |
</ul> |
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<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 |
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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 |
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These changes are in other parts of the page. You can review the |
interpretations. For instance, the list does not include changes in |
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complete list of changes to the page through |
asides, formatting, spelling, punctuation, or other parts of the page. |
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You can review the complete list of changes to the page through |
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the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&view=log">cvsweb |
the <a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&view=log">cvsweb |
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interface</a>.</p> |
interface</a>.</p> |
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There are also <a href="/contact/">other ways to contact</a> |
There are also <a href="/contact/">other ways to contact</a> |
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