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<h2>What is free software?</h2> |
<h2>What is free software?</h2> |
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<h3>The Free Software Definition</h3> |
<h3>The Free Software Definition</h3> |
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<blockquote> |
<blockquote> |
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<p> |
<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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an instrument of unjust power</a>. |
an instrument of unjust power</a>. |
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</p> |
</p> |
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<h4> The four essential freedoms</h4> |
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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: |
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are free. However, if we plan to modify A so that it doesn't use B, |
are free. However, if we plan to modify A so that it doesn't use B, |
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only A needs to be free; B is not pertinent to that plan.</p> |
only A needs to be free; B is not pertinent to that plan.</p> |
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<p> |
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“Free software” does not mean “noncommercial”. A free |
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program must be available for commercial use, commercial development, |
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and commercial distribution. Commercial development of free software |
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is no longer unusual; such free commercial software is very important. |
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You may have paid money to get copies of free software, or you may have |
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obtained copies at no charge. But regardless of how you got your copies, |
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you always have the freedom to copy and change the software, even to |
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<a href="/philosophy/selling.html">sell copies</a>. |
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</p> |
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<p>The rest of this page clarifies certain points about what makes |
<p>The rest of this page clarifies certain points about what makes |
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specific freedoms adequate or not.</p> |
specific freedoms adequate or not.</p> |
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<p>Freedom to distribute (freedoms 2 and 3) means you are free to |
<h4>The freedom to run the program as you wish</h4> |
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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 |
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things means (among other things) that you do not have to ask or pay |
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for permission to do so. |
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</p> |
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<p> |
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You should also have the freedom to make modifications and use them |
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privately in your own work or play, without even mentioning that they |
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exist. If you do publish your changes, you should not be required to |
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notify anyone in particular, or in any particular way. |
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</p> |
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<p> |
<p> |
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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 |
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functionality the program has, or whether it is useful for what you |
functionality the program has, or whether it is useful for what you |
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want to do.</p> |
want to do.</p> |
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<p> |
<h4>The freedom to study the source code and make changes</h4> |
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The freedom to redistribute copies must include binary or executable |
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forms of the program, as well as source code, for both modified and |
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unmodified versions. (Distributing programs in runnable form is necessary |
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for conveniently installable free operating systems.) It is OK if there |
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is no way to produce a binary or executable form for a certain program |
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(since some languages don't support that feature), but you must have the |
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freedom to redistribute such forms should you find or develop a way to |
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make them. |
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</p> |
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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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</p> |
</p> |
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<p> |
<p> |
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Whether a change constitutes an improvement is a subjective matter. |
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If your right to modify a program is limited, in substance, to changes that |
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someone else considers an improvement, that program is not free. |
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</p> |
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<h4>The freedom to redistribute if you wish: basic requirements</h4> |
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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 |
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things means (among other things) that you do not have to ask or pay |
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for permission to do so. |
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</p> |
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<p> |
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You should also have the freedom to make modifications and use them |
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privately in your own work or play, without even mentioning that they |
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exist. If you do publish your changes, you should not be required to |
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notify anyone in particular, or in any particular way. |
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</p> |
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<p> |
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Freedom 3 includes the freedom to release your modified versions |
Freedom 3 includes the freedom to release your modified versions |
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as free software. A free license may also permit other ways of |
as free software. A free license may also permit other ways of |
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releasing them; in other words, it does not have to be |
releasing them; in other words, it does not have to be |
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</p> |
</p> |
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<p> |
<p> |
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In order for these freedoms to be real, they must be permanent and |
The freedom to redistribute copies must include binary or executable |
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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 |
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software has the power to revoke the license, or retroactively add |
unmodified versions. (Distributing programs in runnable form is necessary |
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restrictions to its terms, without your doing anything wrong to give |
for conveniently installable free operating systems.) It is OK if there |
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cause, the software is not free. |
is no way to produce a binary or executable form for a certain program |
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(since some languages don't support that feature), but you must have the |
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freedom to redistribute such forms should you find or develop a way to |
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make them. |
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</p> |
</p> |
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<h4>Copyleft</h4> |
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<p> |
<p> |
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However, certain kinds of rules about the manner of distributing free |
Certain kinds of rules about the manner of distributing free |
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software are acceptable, when they don't conflict with the central |
software are acceptable, when they don't conflict with the central |
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freedoms. For example, <a href="/copyleft/copyleft.html">copyleft</a> |
freedoms. For example, <a href="/copyleft/copyleft.html">copyleft</a> |
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(very simply stated) is the rule that when redistributing the program, |
(very simply stated) is the rule that when redistributing the program, |
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relate to each other. |
relate to each other. |
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</p> |
</p> |
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<p> |
<h4>Rules about packaging and distribution details</h4> |
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“Free software” does not mean “noncommercial”. A free |
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program must be available for commercial use, commercial development, |
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and commercial distribution. Commercial development of free software |
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is no longer unusual; such free commercial software is very important. |
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You may have paid money to get copies of free software, or you may have |
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obtained copies at no charge. But regardless of how you got your copies, |
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you always have the freedom to copy and change the software, even to |
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<a href="/philosophy/selling.html">sell copies</a>. |
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</p> |
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<p> |
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Whether a change constitutes an improvement is a subjective matter. |
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If your right to modify a program is limited, in substance, to changes that |
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someone else considers an improvement, that program is not free. |
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</p> |
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<p> |
<p> |
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However, rules about how to package a modified version are acceptable, |
Rules about how to package a modified version are acceptable, |
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if they don't substantively limit your freedom to release modified |
if they don't substantively limit your freedom to release modified |
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versions, or your freedom to make and use modified versions privately. |
versions, or your freedom to make and use modified versions privately. |
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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 |
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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 |
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alias for the modified version.</p> |
alias for the modified version.</p> |
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<h4>Export regulations</h4> |
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<p> |
<p> |
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Sometimes government <a id="exportcontrol">export control regulations</a> |
Sometimes government <a id="exportcontrol">export control regulations</a> |
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and trade sanctions can constrain your freedom to distribute copies of |
and trade sanctions can constrain your freedom to distribute copies of |
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software nonfree. |
software nonfree. |
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</p> |
</p> |
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<h4>Legal considerations</h4> |
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<p> |
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In order for these freedoms to be real, they must be permanent and |
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irrevocable as long as you do nothing wrong; if the developer of the |
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software has the power to revoke the license, or retroactively add |
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restrictions to its terms, without your doing anything wrong to give |
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cause, the software is not free. |
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</p> |
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<p> |
<p> |
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A free license may not require compliance with the license of a |
A free license may not require compliance with the license of a |
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nonfree program. Thus, for instance, if a license requires you to |
nonfree program. Thus, for instance, if a license requires you to |
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law applies, or where litigation must be done, or both. |
law applies, or where litigation must be done, or both. |
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</p> |
</p> |
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<h4>Contract-based licenses</h4> |
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<p> |
<p> |
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Most free software licenses are based on copyright, and there are limits |
Most free software licenses are based on copyright, and there are limits |
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on what kinds of requirements can be imposed through copyright. If a |
on what kinds of requirements can be imposed through copyright. If a |
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it is nonfree. |
it is nonfree. |
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</p> |
</p> |
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<h4>Use the right words when talking about free software</h4> |
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<p> |
<p> |
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When talking about free software, it is best to avoid using terms |
When talking about free software, it is best to avoid using terms |
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like “give away” or “for free,” because those terms imply that |
like “give away” or “for free,” because those terms imply that |
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“free software”</a> into various languages. |
“free software”</a> into various languages. |
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</p> |
</p> |
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<h4>How we interpret these criteria</h4> |
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<p> |
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Finally, note that criteria such as those stated in this free software |
Finally, note that criteria such as those stated in this free software |
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definition require careful thought for their interpretation. To decide |
definition require careful thought for their interpretation. To decide |
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it easier to see why certain licenses do or don't qualify. |
it easier to see why certain licenses do or don't qualify. |
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</p> |
</p> |
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<h4>Get help with free licenses</h4> |
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<p> |
<p> |
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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 |
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software license, see our <a href="/licenses/license-list.html">list |
software license, see our <a href="/licenses/license-list.html">list |