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自由软件的定义
我们维护本文来彰显自由软件定义，说明什么软件才合适被称为「自由软件」。
「自由软件」关於「自由」而不是价格，「自由 (Free) 」这个概念并不是指「免费的啤酒」，而是指「言论自由」【因为英文的自由和免费视同一个字: free】。
自由软件所指称的软件，其使用者有使用、复制、散布、研究、改写、再利用该软件的自由。更精确地说，自由软件赋予使用者四种自由:
- 不论目的为何，有使用该软件的自由（自由之零）。
- 有研究该软件如何运作的自由，并且得以改写该软件来符合使用者自身的需求（自由之一）。取得该软件之源码为达成此目的之前提。
- 有重新散布该软件的自由，所以每个人都可以藉由散布自由软件来敦亲睦邻（自由之二）。
- 有改善再利用该软件的自由，并且可以发表改写版供公众使用，如此一来，整个社群都可以受惠。如前项，取得该软件之源码为达成此目的之前提（自由之三）。
如果一软件的使用者具有上述四种权利，则该软件得以被称之为「自由软件」。也就是说，使用者必须能够自由地、以不收费或是收取合理的散布费用的方式、在任何时间再散布该软件的原版或是改写版 在任何地方给任何人 使用。如果使用者不必问任何人或是支付任何的许可费用从事这些行为，就表示她／他拥有自由软件所赋予的自由权利。
使用者也应该有自由改写软件的权利，并且可以将这些软件再利用在工作上或是娱乐上。
使用软件的这份自由权适用於任何人、任何组织、任何电脑系统、任何工作性质，不用特别和软件作者或是其他特别的人或单位报备。
再散布软件的自由必须同时适用於原版和改写版软件的二进制码和源码上，如果无法制作二进制码的版本，则此动作可以略过，但是如果后来的使用者找到其它可以制作二进制码的方式，她们必须有再散布二进制码的自由。
为了成就改写并发表改写版的自由，使用者必须有取得该软件源码的管道，所以，取得源码为自由软件之本。
为了使这些自由成真，只要使用者没犯下滔天大罪，这些自由权利不能被改变。如果使用者并未做错事，而该软件的作者却拥有取消或撤回其许可方式的权力，那么该软件不是自由软件。
但是，如果额外的规定不和上述四项主要的自由权利相冲的话，这些有关散布自由软件的额外规定是可被接受的。例如，另类版权 copyleft 规定说，当重新散布该软件时，作者不能加限制拒绝其他人主要的自由权利，这个规定并不和上述的主要自由相冲，反而更进一步保障了使用者的自由软件权益。
使用者可以付费取得 GNU 的软件，或者，使用者也可以免费取得这些软件，但是，不管使用者是如何取得这些软件的，她／他们必须永远有权利复制或是改写这些软件，甚至 贩售 这些软件。
自由软件因此并不是「非商业软件」。自由软件必须适用於商业用途。自由软件的商业开发模式已很常见；这样的自由商业软件相当重要。
如果不影响到后来的使用者发行改写的权利规定，则额外加入的规范如何将一个改写后的自由软件制作为套件的相关规定亦可行。同理，像这类「如果你用这种方式发行软件，你必须让这个软件也能在这种情况下可得」的措辞也是在许可之下的（这类规定也让使用者有该不该发行该软件的选择）。如果许可证要求「在当你发行修订版时，若先前的开发者要求一份拷贝，则你必须提供」的条件，它也是符合自由的。
在 GNU 工程中，我们使用 copyleft 这类许可方式来保护每个使用者都享有这些软件自由，但是 非 copyleft 的自由软件 也同时存在。我们相信有某些重要的原因使得 copyleft 的许可方式较其它自由软件许可方式要好 ，但是如果你的软件不是 在 copyleft 的许可之下，我们也使用它。
欲知自由软件、以 copyleft 许可的软件、和其它种类的软件的相连性，请见 「自由软件的种类」 一文。
有时候，政府 外销管制 和交易许可的规定会限制使用者全球性散布软件的权利和自由，虽然软件开发者／作者没有权力去排除或是消弭这些限制，但是，她／他们可以、 也必须拒绝将这些条件列入自由软件的使用法则中，如此这般，这些官方规定将不会影响到使用者的软件自由，和自由软件相关的人、事、物也因此不在这些政府部门管辖范围之内。
大部份的自由软件的许可证是基於 copyleft ，而可以加诸於其上的要求类型是有限制的。如果一份基於版权的许可证遵守了如上所述的自由时，那么就不太可能会遇上我们从未预期过的其它类型的问题（虽然偶尔还是会有）。不过，有一些自由软件的许可证是基於合同的条款，而合同可以被加诸较大程度的可能限制。这表示像是这样的许可证，会有许多可能的方式变得受限到无法接受，因而成为「非自由」的。
我们实在无法列出所有无法接受的可能的合同限制。如果一份基於合同的许可证，以一种基於版权的许可证所无法的不寻常方式，限制了使用者，并且不能如本文所述的视为合格〔的自由条款〕，我们将会试著审度这合同，并且很有可能认定它是非自由的。
当谈到自由软件时，最好避免使用「给」或是「免费」这类的措辞，因为这些措辞会给人给人「free」是指「价格上的免费」的误导，而忽略了使用软件自由的真义。有些词语像 「盗版」就有类似的涵义，我们希望自由软件的使用者不会想被这样指称。有关讨论这些措辞的用法，详见 「容易混淆的词语，请尽量避免」 一文，我们也有 「自由软件一词的翻译」 的多种语言版本。
最后，请注意，这些有关自由软件定义的标准需要审慎的诠释。我们根据某一软件选定的许可方式是否符合上述四点软件自由的精神和重点文字，来决定该软件是否符合自由软件的标准。如果某一软件含有不公平、违背上述四点自由软件精神的限制，就算该软件发行了，我们拒绝使用它。有时候，一份许可证会引发一些讨论，在接受它成为一份自由软件许可证之前，需要我们和一些律师法律专家们共同来判断和思考，当我们达成共识的时候，我们会更新自由软件标准，让使用者更容易了解什么许可方式是符合或是不符合自由软件定义的。
如果你对某份特定的许可方式是否符合自由软件的许可方式有兴趣，请见我们的 「许可方式一览表」 一文，如果你感兴趣的许可方式不在我们的列表中，请直接透过 email 问我们。来信请寄 <[email protected]> 。
可能的情况下，如果你真的需要一份新的许可证，那么在我们的协助下你可以确定那许可证是否真是自由软件许可证，从而避开许多实际上的问题。
其它团体已经开始使用「开放源码 」一词，以用来指称与「自由软件 」在某种程度意义相当，但是仍不尽相同的事物。我们倾向於使用「自由软件 」的原因在於，一旦你曾听过它意指自由，而非免费，那么 你就可以从它的称呼上知道它所著重的是自由了 。
进阶阅读
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请将失效链接以及其它网页的更正（或建议）送到 [email protected] 。
请查阅 翻译读我 以取得关於「协调」与「寄交」翻译的信息。
请将有关翻译的问题送到 GNU/CTT 的 翻译人员 。
翻译： 林钰维 | Yuwei Lin | yuwei {at} ylin {dot} org 。
验证： 刘 昭宏 <[email protected]> 。
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
Verbatim copying and distribution of this entire article is permitted in any medium without royalty provided this notice is preserved.
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Updated: $Date: 2004/11/18 00:44:00 $ $Author: chstoneliu $
Translations of this page
Categories of Free and Non-Free Software
Here is a glossary of various categories of software that are often mentioned in discussions of free software. It explains which categories overlap or are part of other categories.
Table of Contents
- Other Texts to Read
- ``Free software''
- ``Open source''
- ``Public domain software''
- ``Copylefted software''
- ``Non-copylefted free software''
- ``GPL-covered software''
- ``The GNU system''
- ``GNU programs''
- ``GNU software''
- ``Non-free software''
- ``Semi-free software''
- ``Proprietary software''
- ``Shareware''
- ``Freeware''
- ``Private (custom) software''
- ``Commercial software''
- Other Texts to Read
Also note Confusing Words which You Might Want to Avoid.
This diagram by Chao-Kuei explains the different categories of software. It's available as an XFig file, as a JPEG picture and as a 1.5 magnified PNG image.
- Free software
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Free software is software that comes with permission for anyone to use, copy, and distribute, either verbatim or with modifications, either gratis or for a fee. In particular, this means that source code must be available. ``If it's not source, it's not software.'' This is a simplified definition; see also the full definition.
If a program is free, then it can potentially be included in a free operating system such as GNU, or free versions of the GNU/Linux system.
There are many different ways to make a program free---many questions of detail, which could be decided in more than one way and still make the program free. Some of the possible variations are described below. For information on specific free software licenses, see the license list page.
Free software is a matter of freedom, not price. But proprietary software companies sometimes use the term ``free software'' to refer to price. Sometimes they mean that you can obtain a binary copy at no charge; sometimes they mean that a copy is included on a computer that you are buying. This has nothing to do with what we mean by free software in the GNU project.
Because of this potential confusion, when a software company says its product is free software, always check the actual distribution terms to see whether users really have all the freedoms that free software implies. Sometimes it really is free software; sometimes it isn't.
Many languages have two separate words for ``free'' as in freedom and ``free'' as in zero price. For example, French has ``libre'' and ``gratuit''. Not so English; there is a word ``gratis'' that refers unambiguously to price, but no common adjective that refers unambiguously to freedom. So if you are speaking another language, we suggest you translate ``free'' into your language to make it clearer. See our list of translations of the term "free software" into various other languages.
Free software is often more reliable than non-free software.
Open Source software -
The term ``open source'' software is used by some people to mean more or less the same thing as free software. However, their criteria are somewhat lax; they accept some license restrictions that we consider too restrictive.
We prefer the term ``free software'' because it refers to freedom--something that the term ``open source'' does not do.
Public domain software -
Public domain software is software that is not copyrighted. If the source code is in the public domain, that is a special case of non-copylefted free software , which means that some copies or modified versions may not be free at all.
In some cases, an executable program can be in the public domain but the source code is not available. This is not free software, because free software requires accesibility of source code. Meanwhile, most free software is not in the public domain; it is copyrighted, and the copyright holders have legally given permission for everyone to use it in freedom, using a free software license.
Sometimes people use the term ``public domain'' in a loose fashion to mean ``free'' or ``available gratis.'' However, ``public domain'' is a legal term and means, precisely, ``not copyrighted''. For clarity, we recommend using ``public domain'' for that meaning only, and using other terms to convey the other meanings.
Under the Berne Convention, which most countries have signed, anything written down is automatically copyrighted. This includes programs. Therefore, if you want a program you have written to be in the public domain, you must take some legal steps to disclaim the copyright on it; otherwise, the program is copyrighted.
Copylefted software -
Copylefted software is free software whose distribution terms do not let redistributors add any additional restrictions when they redistribute or modify the software. This means that every copy of the software, even if it has been modified, must be free software.
In the GNU Project, we copyleft almost all the software we write, because our goal is to give every user the freedoms implied by the term ``free software.'' See Copylefted for more explanation of how copyleft works and why we use it.
Copyleft is a general concept; to actually copyleft a program, you need to use a specific set of distribution terms. There are many possible ways to write copyleft distribution terms, so in principle there can be many copyleft free software licenses. However, in actual practice nearly all copylefted software uses the GNU General Public License. Two different copyleft licenses are usually ``incompatible'', which means it is illegal to merge the code using one license with the code using the other license; therefore, it is good for the community if people use a single copyleft license.
Non-copylefted free software -
Non-copylefted free software comes from the author with permission to redistribute and modify, and also to add additional restrictions to it.
If a program is free but not copylefted, then some copies or modified versions may not be free at all. A software company can compile the program, with or without modifications, and distribute the executable file as a proprietary software product.
The X Window System illustrates this. The X Consortium releases X11 with distribution terms that make it non-copylefted free software. If you wish, you can get a copy which has those distribution terms and is free. However, there are non-free versions as well, and there are popular workstations and PC graphics boards for which non-free versions are the only ones that work. If you are using this hardware, X11 is not free software for you. The developers of X11 even made X11 non-free for a while.
GPL-covered software - The GNU GPL (General Public License) is one specific set of distribution terms for copylefting a program. The GNU Project uses it as the distribution terms for most GNU software. The GNU system
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The GNU system is a complete free Unix-like operating system.
A Unix-like operating system consists of many programs. The GNU system includes all the GNU software, as well as many other packages such as the X Window System and TeX which are not GNU software.
We have been developing and accumulating components for the GNU system since 1984; the first test release of a ``complete GNU system'' was in 1996. In 2001 the GNU system with the Hurd began working reliably. In the mean time, the GNU/Linux system, an offshoot of the GNU system which uses Linux as the kernel, became a great success in the 90s.
Since the purpose of GNU is to be free, every single component in the GNU system has to be free software. They don't all have to be copylefted, however; any kind of free software is legally suitable to include if it helps meet technical goals. We can and do use non-copylefted free software such as the X Window System.
GNU programs - ``GNU programs'' is equivalent to GNU software. A program Foo is a GNU program if it is GNU software. We also sometimes say it is a ``GNU package''. GNU software
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GNU software is software that is released under the auspices of the GNU Project. If a program is GNU software, we also say that it is a GNU program or a GNU package. The README or manual of a GNU package should say it is one; also, the Free Software Directory indentifies all GNU packages.
Most GNU software is copylefted , but not all; however, all GNU software must be free software.
Some GNU software is written by staff of the Free Software Foundation, but most GNU software is contributed by volunteers. Some contributed software is copyrighted by the Free Software Foundation; some is copyrighted by the contributors who wrote it.
Non-free software - Non-free software is any software that is not free. This includes semi-free software and proprietary software. Semi-free software
-
Semi-free software is software that is not free, but comes with permission for individuals to use, copy, distribute, and modify (including distribution of modified versions) for non-profit purposes. PGP is an example of a semi-free program.
Semi-free software is much better ethically than proprietary software, but it still poses problems, and we cannot use it in a free operating system.
The restrictions of copyleft are designed to protect the essential freedoms for all users. For us, the only justification for any substantive restriction on using a program is to prevent other people from adding other restrictions. Semi-free programs have additional restrictions, motivated by purely selfish goals.
It is impossible to include semi-free software in a free operating system. This is because the distribution terms for the operating system as a whole are the conjunction of the distribution terms for all the programs in it. Adding one semi-free program to the system would make the system as a whole just semi-free. There are two reasons we do not want that to happen:
- We believe that free software should be for everyone--including businesses, not just schools and hobbyists. We want to invite business to use the whole GNU system, and therefore we must not include a semi-free program in it.
- Commercial distribution of free operating systems, including the GNU/Linux system, is very important, and users appreciate the convenience of commercial CD-ROM distributions. Including one semi-free program in an operating system would cut off commercial CD-ROM distribution for it.
The Free Software Foundation itself is non-commercial, and therefore we would be legally permitted to use a semi-free program ``internally''. But we don't do that, because that would undermine our efforts to obtain a program which we could also include in GNU.
If there is a job that needs doing with software, then until we have a free program to do the job, the GNU system has a gap. We have to tell volunteers, ``We don't have a program yet to do this job in GNU, so we hope you will write one.'' If we ourselves used a semi-free program to do the job, that would undermine what we say; it would take away the impetus (on us, and on others who might listen to our views) to write a free replacement. So we don't do that.
Proprietary software -
Proprietary software is software that is not free or semi-free. Its use, redistribution or modification is prohibited, or requires you to ask for permission, or is restricted so much that you effectively can't do it freely.
The Free Software Foundation follows the rule that we cannot install any proprietary program on our computers except temporarily for the specific purpose of writing a free replacement for that very program. Aside from that, we feel there is no possible excuse for installing a proprietary program.
For example, we felt justified in installing Unix on our computer in the 1980s, because we were using it to write a free replacement for Unix. Nowadays, since free operating systems are available, the excuse is no longer applicable; we have eliminated all our non-free operating systems, and any new computer we install must run a completely free operating system.
We don't insist that users of GNU, or contributors to GNU, have to live by this rule. It is a rule we made for ourselves. But we hope you will decide to follow it too.
Freeware - The term ``freeware'' has no clear accepted definition, but it is commonly used for packages which permit redistribution but not modification (and their source code is not available). These packages are not free software, so please don't use ``freeware'' to refer to free software. Shareware
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Shareware is software which comes with permission for people to redistribute copies, but says that anyone who continues to use a copy is required to pay a license fee.
Shareware is not free software, or even semi-free. There are two reasons it is not:
- For most shareware, source code is not available; thus, you cannot modify the program at all.
- Shareware does not come with permission to make a copy and install it without paying a license fee, not even for individuals engaging in nonprofit activity. (In practice, people often disregard the distribution terms and do this anyway, but the terms don't permit it.)
Private software -
Private or custom software is software developed for one user (typically an organization or company). That user keeps it and uses it, and does not release it to the public either as source code or as binaries.
A private program is free software in a trivial sense if its unique user has full rights to it. However, in a deeper sense, it does not really make sense to pose the question of whether such a program is free software or not.
In general we do not believe it is wrong to develop a program and not release it. There are occasions when a program is so useful that withholding it from release is treating humanity badly. However, most programs are not that marvelous, and withholding them is not particularly harmful. Thus, there is no conflict between the development of private or custom software and the principles of the free software movement.
Nearly all employment for programmers is in development of custom software; therefore most programming jobs are, or could be, done in a way compatible with the free software movement.
Commercial Software -
Commercial software is software being developed by a business which aims to make money from the use of the software. ``Commercial'' and ``proprietary'' are not the same thing! Most commercial software is proprietary, but there is commercial free software, and there is non-commercial non-free software.
For example, GNU Ada is always distributed under the terms of the GNU GPL, and every copy is free software; but its developers sell support contracts. When their salesmen speak to prospective customers, sometimes the customers say, ``We would feel safer with a commercial compiler.'' The salesmen reply, ``GNU Ada is a commercial compiler; it happens to be free software.''
For the GNU Project, the emphasis is in the other order: the important thing is that GNU Ada is free software; whether it is commercial is not a crucial question. However, the additional development of GNU Ada that results from its being commercial is definitely beneficial.
Please help spread the awareness that commercial free software is possible. You can do this by making an effort not to say ``commercial'' when you mean ``proprietary.''
Other Texts to Read
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Copyright (C) 1996, 1997, 1998, 2001 Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA
Verbatim copying and distribution of this entire article is permitted in any medium without royalty provided this notice is preserved.
Updated: $Date: 2004/10/26 07:03:10 $ $Author: rms $