The Free Software Definition

-We maintain this free software definition to show clearly what must be -true about a particular software program for it to be considered -free software.

-``Free software'' is a matter of liberty, not price. To understand the -concept, you should think of ``free'' as in ``free speech,'' not as in -``free beer.''

-Free software is a matter of the users' freedom to run, copy, -distribute, study, change and improve the software. More precisely, -it refers to four kinds of freedom, for the users of the software:

-A program is free software if users have all of these freedoms. -Thus, you should be free to redistribute copies, either with or -without modifications, either gratis or charging a fee for -distribution, to anyone anywhere. Being -free to do these things means (among other things) that you do not -have to ask or pay for permission.

In any given scenario, these freedoms must apply to whatever code +we plan to make use of, or lead others to make use of. For instance, +consider a program A which automatically launches a program B to +handle some cases. If we plan to distribute A as it stands, that +implies users will need B, so we need to judge whether both A and B +are free. However, if we plan to modify A so that it doesn't use B, +only A needs to be free; we can ignore B.

The rest of this page clarifies certain points about what makes +specific freedoms adequate or not.

Freedom to distribute (freedoms 2 and 3) means you are free to +redistribute copies, either with or without modifications, either +gratis or charging a fee for distribution, to +anyone anywhere. Being free to do these +things means (among other things) that you do not have to ask or pay +for permission to do so. +

You should also have the freedom to make modifications and use them privately in your own work or play, without even mentioning that they exist. If you do publish your changes, you should not be required to -notify anyone in particular, or in any particular way.

-The freedom to use a program means the freedom for any kind of person -or organization to use it on any kind of computer system, for any kind -of overall job, and without being required to communicate subsequently -with the developer or any other specific entity.

+The freedom to run the program as you wish means that you are not +forbidden or stopped from doing so. It has nothing to do with what +functionality the program has, or whether it is useful for what you +want to do.

The freedom to redistribute copies must include binary or executable forms of the program, as well as source code, for both modified and -unmodified versions. (Distributing programs in runnable form is -necessary for conveniently installable free operating systems.) It is -ok if there is no way to produce a binary or executable form for a -certain program (since some languages don't support that feature), but -you must have the freedom to redistribute such forms should you find -or develop a way to make them.

-In order for the freedoms to make changes, and to publish improved -versions, to be meaningful, you must have access to the source code of -the program. Therefore, accessibility of source code is a necessary -condition for free software.

+In order for freedoms 1 and 3 (the freedom to make changes and the +freedom to publish the changed versions) to be meaningful, you must have +access to the source code of the program. Therefore, accessibility of +source code is a necessary condition for free software. Obfuscated +“source code” is not real source code and does not count +as source code. +

+Freedom 1 includes the freedom to use your changed version in place of +the original. If the program is delivered in a product designed to +run someone else's modified versions but refuse to run yours — a +practice known as “tivoization” or “lockdown”, +or (in its practitioners' perverse terminology) as “secure +boot” — freedom 1 becomes an empty pretense rather than a +practical reality. These binaries are not free +software even if the source code they are compiled from is free. +

One important way to modify a program is by merging in available free subroutines and modules. If the program's license says that you -cannot merge in an existing module, such as if it requires you to be -the copyright holder of any code you add, then the license is too -restrictive to qualify as free.

-In order for these freedoms to be real, they must be irrevocable as -long as you do nothing wrong; if the developer of the software has the -power to revoke the license, without your doing anything to give -cause, the software is not free.

+Freedom 3 includes the freedom to release your modified versions +as free software. A free license may also permit other ways of +releasing them; in other words, it does not have to be +a copyleft license. However, a +license that requires modified versions to be nonfree does not qualify +as a free license. +

+In order for these freedoms to be real, they must be permanent and +irrevocable as long as you do nothing wrong; if the developer of the +software has the power to revoke the license, or retroactively add +restrictions to its terms, without your doing anything wrong to give +cause, the software is not free. +

However, certain kinds of rules about the manner of distributing free software are acceptable, when they don't conflict with the central -freedoms. For example, copyleft (very simply stated) is the rule that -when redistributing the program, you cannot add restrictions to deny -other people the central freedoms. This rule does not conflict with -the central freedoms; rather it protects them.

-You may have paid money to get copies of free software, or you -may have obtained copies at no charge. But regardless of how you got -your copies, you always have the freedom to copy and change the -software, even to sell copies.

-``Free software'' does not mean ``non-commercial''. A free program -must be available for commercial use, commercial development, and -commercial distribution. Commercial development of free software is -no longer unusual; such free commercial software is very important.

-Rules about how to package a modified version are acceptable, if they -don't substantively block your freedom to release modified versions, -or your freedom to make and use modified versions privately. Rules -that ``if you make your version available in this way, you must make -it available in that way also'' can be acceptable too, on the same -condition. (Note that such a rule still leaves you the choice of -whether to publish your version at all.) Rules that require release +freedoms. For example, copyleft +(very simply stated) is the rule that when redistributing the program, +you cannot add restrictions to deny other people the central freedoms. +This rule does not conflict with the central freedoms; rather it +protects them. +

+In the GNU project, we use copyleft to protect the four freedoms +legally for everyone. We believe there are important reasons why +it is better to use +copyleft. However, + +noncopylefted free software is ethical +too. See Categories of Free +Software for a description of how “free software,” +“copylefted software” and other categories of software +relate to each other. +

+“Free software” does not mean “noncommercial”. A free +program must be available for commercial use, commercial development, +and commercial distribution. Commercial development of free software +is no longer unusual; such free commercial software is very important. +You may have paid money to get copies of free software, or you may have +obtained copies at no charge. But regardless of how you got your copies, +you always have the freedom to copy and change the software, even to +sell copies. +

+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. +

+However, rules about how to package a modified version are acceptable, +if they don't substantively limit your freedom to release modified +versions, or your freedom to make and use modified versions privately. +Thus, it is acceptable for the license to require that you change the +name of the modified version, remove a logo, or identify your +modifications as yours. As long as these requirements are not so +burdensome that they effectively hamper you from releasing your +changes, they are acceptable; you're already making other changes to +the program, so you won't have trouble making a few more. +

+Rules that “if you make your version available in this way, you +must make it available in that way also” can be acceptable too, +on the same condition. An example of such an acceptable rule is one +saying that if you have distributed a +modified version and a previous developer asks for a copy of it, you +must send one. (Note that such a rule still leaves you the choice of +whether to distribute your version at all.) Rules that require release of source code to the users for versions that you put into public use -are also acceptable. It is also acceptable for the license to require -that, if you have distributed a modified version and a previous -developer asks for a copy of it, you must send one, or that you -identify yourself on your modifications. -

-In the GNU project, we use ``copyleft'' -to protect these freedoms legally for everyone. But -non-copylefted -free software also exists. We believe there are -important reasons why it is -better to use copyleft, but if your program is non-copylefted free -software, we can still use it.

-See Categories of Free Software -for a description of how ``free software,'' ``copylefted software'' and -other categories of software relate to each other.

-Sometimes government export control -regulations and trade sanctions can constrain your freedom to -distribute copies of programs internationally. Software developers do -not have the power to eliminate or override these restrictions, but -what they can and must do is refuse to impose them as conditions of -use of the program. In this way, the restrictions will not affect -activities and people outside the jurisdictions of these governments.

-Most free software licenses are based on copyright, and there are -limits on what kinds of requirements can be imposed through copyright. -If a copyright-based license respects freedom in the ways described -above, it is unlikely to have some other sort of problem that we never -anticipated (though this does happen occasionally). However, some -free software licenses are based on contracts, and contracts can -impose a much larger range of possible restrictions. That means there -are many possible ways such a license could be unacceptably -restrictive and non-free.

-We can't possibly list all the possible contract restrictions that -would be unacceptable. If a contract-based license restricts the user -in an unusual way that copyright-based licenses cannot, and which -isn't mentioned here as legitimate, we will have to think about it, -and we will probably decide it is non-free.

-When talking about free software, it is best to avoid using terms like -``give away'' or ``for free'', because those terms imply that the -issue is about price, not freedom. Some common terms such as -``piracy'' embody opinions we hope you won't endorse. See -Confusing Words and Phrases -that are Worth Avoiding for a discussion of these terms. -We also have a list of translations -of "free software" into various languages.

-Finally, note that criteria such as those stated in this free software -definition require careful thought for their interpretation. To -decide whether a specific software license qualifies as a free -software license, we judge it based on these criteria to determine -whether it fits their spirit as well as the precise words. If a -license includes unconscionable restrictions, we reject it, even if we -did not anticipate the issue in these criteria. Sometimes a license -requirement raises an issue that calls for extensive thought, -including discussions with a lawyer, before we can decide if the -requirement is acceptable. When we reach a conclusion about a new -issue, we often update these criteria to make it easier to see why -certain licenses do or don't qualify.

-If you are interested in whether a specific license qualifies as a -free software license, see our list of licenses. If the -license you are concerned with is not listed there, you can ask us -about it by sending us email at <licensing@gnu.org>.

-If you are contemplating writing a new license, please contact the FSF -by writing to that address. The proliferation of different free -software licenses means increased work for users in understanding the -licenses; we may be able to help you find an existing Free Software -license that meets your needs. +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.

+Sometimes government export control regulations +and trade sanctions can constrain your freedom to distribute copies of +programs internationally. Software developers do not have the power to +eliminate or override these restrictions, but what they can and must do +is refuse to impose them as conditions of use of the program. In this +way, the restrictions will not affect activities and people outside the +jurisdictions of these governments. Thus, free software licenses +must not require obedience to any nontrivial export regulations as a +condition of exercising any of the essential freedoms.

-If that isn't possible, if you really need a new license, with our -help you can ensure that the license really is a Free Software license -and avoid various practical problems. +Merely mentioning the existence of export regulations, without making +them a condition of the license itself, is acceptable since it does +not restrict users. If an export regulation is actually trivial for +free software, then requiring it as a condition is not an actual +problem; however, it is a potential problem, since a later change in +export law could make the requirement nontrivial and thus render the +software nonfree.

-Another group has started using the term "open source" to mean -something close (but not identical) to "free software". We prefer the -term "free software" because, once you have heard it refers to freedom -rather than price, it calls -to mind freedom. The word "open" never does that.

Beyond Software

-Please send FSF & GNU inquiries to -gnu@gnu.org. -There are also other ways to contact -the FSF. -
-Please send broken links and other corrections (or suggestions) to -webmasters@gnu.org. +Software manuals must be free, +for the same reasons that software must be free, and because the +manuals are in effect part of the software.

-Please see the -Translations -README for information on coordinating and submitting -translations of this article. +The same arguments also make sense for other kinds of works of +practical use — that is to say, works that embody useful knowledge, +such as educational works and reference +works. Wikipedia is the best-known +example.

-Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free -Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA -02110, USA -
-Verbatim copying and distribution of this entire article is -permitted in any medium without royalty provided this notice is -preserved. +Any kind of work can be free, and the definition of free software +has been extended to a definition of +free cultural works applicable to any kind of works.

Open Source?

-Updated: +Another group has started using the term “open source” to mean +something close (but not identical) to “free software”. We +prefer the term “free software” because, once you have heard that +it refers to freedom rather than price, it calls to mind freedom. The +word “open” +never refers to freedom. +

+ +

History

+ +

From time to time we revise this Free Software Definition. Here is +the list of substantive changes, along with links to show exactly what +was changed.

+ +

Version +1.141: Clarify which code needs to be free.
Version +1.135: Say each time that freedom 0 is the freedom to run the program +as you wish.
Version +1.134: Freedom 0 is not a matter of the program's functionality.
Version +1.131: A free license may not require compliance with a nonfree license +of another program.
Version +1.129: State explicitly that choice of law and choice of forum +specifications are allowed. (This was always our policy.)
Version +1.122: An export control requirement is a real problem if the +requirement is nontrivial; otherwise it is only a potential problem.
Version +1.118: Clarification: the issue is limits on your right to modify, +not on what modifications you have made. And modifications are not limited +to “improvements”
Version +1.111: Clarify 1.77 by saying that only +retroactive restrictions are unacceptable. The copyright +holders can always grant additional permission for use of the +work by releasing the work in another way in parallel.
Version +1.105: Reflect, in the brief statement of freedom 1, the point +(already stated in version 1.80) that it includes really using your modified +version for your computing.
Version +1.92: Clarify that obfuscated code does not qualify as source code.
Version +1.90: Clarify that freedom 3 means the right to distribute copies +of your own modified or improved version, not a right to participate +in someone else's development project.
Version +1.89: Freedom 3 includes the right to release modified versions as +free software.
Version +1.80: Freedom 1 must be practical, not just theoretical; +i.e., no tivoization.
Version +1.77: Clarify that all retroactive changes to the license are +unacceptable, even if it's not described as a complete +replacement.
Version +1.74: Four clarifications of points not explicit enough, or stated +in some places but not reflected everywhere: +
- "Improvements" does not mean the license can +substantively limit what kinds of modified versions you can release. +Freedom 3 includes distributing modified versions, not just changes.
- The right to merge in existing modules +refers to those that are suitably licensed.
- Explicitly state the conclusion of the point about export controls.
- Imposing a license change constitutes revoking the old license.
+
Version +1.57: Add "Beyond Software" section.
Version +1.46: Clarify whose purpose is significant in the freedom to run +the program for any purpose.
Version +1.41: Clarify wording about contract-based licenses.
Version +1.40: Explain that a free license must allow to you use other +available free software to create your modifications.
Version +1.39: Note that it is acceptable for a license to require you to +provide source for versions of the software you put into public +use.
Version +1.31: Note that it is acceptable for a license to require you to +identify yourself as the author of modifications. Other minor +clarifications throughout the text.
Version +1.23: Address potential problems related to contract-based +licenses.
Version +1.16: Explain why distribution of binaries is important.
Version +1.11: Note that a free license may require you to send a copy of +versions you distribute to the author.

+ +

There are gaps in the version numbers shown above because there are +other changes in this page that do not affect the definition or its +interpretations. For instance, the list does not include changes in +asides, formatting, spelling, punctuation, or other parts of the page. +You can review the complete list of changes to the page through +the cvsweb +interface.

+ + +

What is free software?

Other Texts to Read

Beyond Software

Open Source?

History