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<title>What is free software? |
<title>What is free software? |
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- GNU Project - Free Software Foundation</title> |
- GNU Project - Free Software Foundation</title> |
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<meta http-equiv="Keywords" content="GNU, FSF, Free Software Foundation, Linux, Emacs, GCC, Unix, Free Software, Operating System, GNU Kernel, HURD, GNU HURD, Hurd" /> |
<meta http-equiv="Keywords" content="GNU, FSF, Free Software Foundation, Linux, Emacs, GCC, Unix, Free Software, Operating System, GNU Kernel, HURD, GNU HURD, Hurd" /> |
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<meta http-equiv="Description" content="Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use." /> |
<meta http-equiv="Description" content="Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use." /> |
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<h2>What is free software?</h2> |
<h2>What is free software?</h2> |
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<div class="article"> |
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<h3>The Free Software Definition</h3> |
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<blockquote class="note" id="fsf-licensing"><p style="font-size: 80%"> |
<blockquote class="note" id="fsf-licensing"><p style="font-size: 80%"> |
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Have a question about free software licensing not answered here? |
Have a question about free software licensing not answered here? |
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See our other <a href="http://www.fsf.org/licensing">licensing resources</a>, |
See our other <a href="http://www.fsf.org/licensing">licensing resources</a>, |
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at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p> |
at <a href="mailto:licensing@fsf.org">licensing@fsf.org</a>.</p> |
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</blockquote> |
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<h3>The Free Software Definition</h3> |
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<blockquote> |
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<p> |
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The free software definition presents the criteria for whether a |
The free software definition presents the criteria for whether a |
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particular software program qualifies as free software. From time to |
particular software program qualifies as free software. From time to |
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below for a list of changes that affect the definition of free |
below for a list of changes that affect the definition of free |
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software. |
software. |
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</p> |
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</blockquote> |
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<p> |
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“Open source” is something different: it has a very |
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different philosophy based on different values. Its practical |
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definition is different too, but nearly all open source programs are |
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in fact free. We explain the |
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difference in <a href="/philosophy/open-source-misses-the-point.html"> |
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Why “Open Source” misses the point of Free Software</a>. |
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</div> |
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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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<p> |
<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: <a href="#f1">[1]</a> |
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</p> |
</p> |
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<ul> |
<ul class="important"> |
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<li>The freedom to run the program as you wish, |
<li>The freedom to run the program as you wish, |
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for any purpose (freedom 0).</li> |
for any purpose (freedom 0).</li> |
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<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 |
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does your computing as you wish (freedom 1). Access to the source |
does your computing as you wish (freedom 1). Access to the source |
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code is a precondition for this. |
code is a precondition for this. |
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</li> |
</li> |
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<li>The freedom to redistribute copies so you can help your neighbor |
<li>The freedom to redistribute copies so you can help others |
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(freedom 2). |
(freedom 2). |
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</li> |
</li> |
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<li>The freedom to distribute copies of your modified versions |
<li>The freedom to distribute copies of your modified versions |
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<a href="/philosophy/selling.html">sell copies</a>. |
<a href="/philosophy/selling.html">sell copies</a>. |
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</p> |
</p> |
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<p>The rest of this page clarifies certain points about what makes |
<p> |
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specific freedoms adequate or not.</p> |
A free program must offer the four freedoms to any user that obtains a |
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copy of the software, provided the user has complied thus far with the |
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conditions of the free license covering the software. Putting some of |
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the freedoms off limits to some users, or requiring that users pay, in |
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money or in kind, to exercise them, is tantamount to not granting the |
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freedoms in question, and thus renders the program nonfree. |
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</p> |
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<h3>Clarifying the line at various points</h3> |
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<p>In the rest of this article we expain more precisely how far the |
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various freedoms need to extend, on various issues, in order for a |
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program to be free.</p> |
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<h4>The freedom to run the program as you wish</h4> |
<h4>The freedom to run the program as you wish</h4> |
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<p> |
<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 the changed versions) to be meaningful, you must have |
freedom to publish the changed versions) to be meaningful, you need to 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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word “open” <a href="/philosophy/open-source-misses-the-point.html"> |
word “open” <a href="/philosophy/open-source-misses-the-point.html"> |
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never refers to freedom</a>. |
never refers to freedom</a>. |
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</p> |
</p> |
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</div> |
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<h3 id="History">History</h3> |
<h3 id="History">History</h3> |
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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=1.162&r2=1.163">Version |
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1.163</a>: Clarify that the four freedoms apply to any and all users, |
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and that requiring users to pay to exercise some of these freedoms is |
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a way of denying them.</li> |
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<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.152&r2=1.153">Version |
<li><a href="http://web.cvs.savannah.gnu.org/viewvc/www/philosophy/free-sw.html?root=www&r1=1.152&r2=1.153">Version |
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1.153</a>: Clarify that freedom to run the program means nothing stops |
1.153</a>: Clarify that freedom to run the program means nothing stops |
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you from making it run.</li> |
you from making it run.</li> |
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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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<h3 style="font-size:1em">Footnote</h3> |
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<ol> |
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<li id="f1">The reason they are numbered 0, 1, 2 and 3 is historical. Around |
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1990 there were three freedoms, numbered 1, 2 and 3. Then we realized that |
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the freedom to run the program needed to be mentioned explicitly. |
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It was clearly more basic than the other three, so it properly should |
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precede them. Rather than renumber the others, we made it freedom 0.</li> |
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</ol> |
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<p>Copyright © 1996, 2002, 2004-2007, 2009-2017 |
<p>Copyright © 1996, 2002, 2004-2007, 2009-2019 |
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Free Software Foundation, Inc.</p> |
Free Software Foundation, Inc.</p> |
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<p>This page is licensed under a <a rel="license" |
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