I know that FOSS is the acronym for Free "and" Open Source Software.

Or does it mean Free "or" Open Source Software?
For example: to be considered FOSS, a program's license must be included in both FSF and OSI lists of approved licenses, or the belonging to only one of the two lists is enough? Fedora uses only FOSS software; does this mean that licenses adopted by software included in Fedora should be approved by both FSF and OSI?

Any help will be very appreciated.

EDIT: This question is essentially he same as http://programmers.stackexchange.com/questions/21907/open-source-but-not-free-software-or-vice-versa, and so I understand that it has to be closed. However thanks to all for your answers.

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    This question appears to be off-topic because it is about deciding which definition of “FOSS” is right, i.e. it's about a political debate. Nov 29 '14 at 21:00
  • FOSS stands for “Free, Open Source Software”, i.e. the connector is and. But which definitions of “free” and “open source” are the right ones is not consensual, once you go deeper than the approximation level at which they are synonyms. Nov 29 '14 at 21:01

FOSS is an acronym for Free and Open Source Software. However, free is meant as freedom, not free in price.

“Free software” means software that respects users' freedom and community. Roughly, it means that the users have the freedom to run, copy, distribute, study, change and improve the software. Thus, “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”.

You can find many definitions and guides on the FSF (Free Software Foundation) home page and on the GNU (GNU's Not Unix) page.

As @nssnd mentioned, there are four levels of freedom, you can read a lot about them on the GNU's The Free Software Definition page.

You can read about various Open Source licenses here.

In conclusion, FOSS is not equivalent with priceless software, it is more like a directive for open sourced software with granted freedom on various levels (depending on the license). For this, a license doesn't need to be included in any of those lists. If a software follows the Open Source directives and its license is compatible with at least one of the Open Source licenses, I think it is considered FOSS. For example a software with Beerware license is a FOSS software, although it isn't on the approved license list, because it isn't among the widespread Open Source licenses.

  • Thanks, I agree, but this is not an answer to my question. Nov 28 '14 at 15:37
  • @user2431763 I have expanded my answer, please take a look at it. Nov 28 '14 at 15:54
  • Thanks for your reply. Please correct me if I'm wrong: Do you say that a FOSS software is one that follows both the FSD (gnu.org/philosophy/free-sw.html) and the OSD (opensource.org/osd-annotated), no matter if his license appears in their lists? I agree: lists are not complete. But if that license appears in one of the two list's rejected licenses, then that license doesn't follow one of the two definitions. So is it still FOSS? Nov 28 '14 at 20:58
  • Exactly. The philosophy of the two organizations doesn't really differs. The core concept and set of ideas are basically the same. It isn't necessary for an Open Source license to be present in the list of approved licenses, however, if one is present in the list of the rejected ones, it has some major problems. Note that most of FOSS products will come under accepted licenses. Nov 28 '14 at 21:17
  • Theoretically, a rejected license can be FOSS, but as these organizations are working with various forums and mailing lists, taking into a big community, this is very unlikely. Nov 28 '14 at 21:37

FOSS means free "and" open, so software must be free and open-sourced, this is a requirement. So if product belongs to free software (has free license), it is open-source by default. But if it's open-sourced it doesn't mean that it is free, it can be considered as non-free if license does not permit you use this soft for (from wikipedia):

  • The freedom to run the program for any purpose.
  • The freedom to study how the program works, and change it to make it do what you wish.
  • The freedom to redistribute copies so you can help your neighbor.
  • The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits.

Freedoms 1 and 4 require source code to be available because studying and modifying software without its source code can range from highly impractical to nearly impossible.

  • So "NASA Open Source Agreement ver. 1.3" is not FOSS, as it's included in OSI license list but not in FSF list. Do you agree? Nov 28 '14 at 15:28
  • This license is not a free software license, you're right.
    – kirill-a
    Nov 28 '14 at 15:30
  • While reading "gnu.org/philosophy/categories.en.html" I noticed: "nearly all free software is open source, and nearly all open source software is free". This let me think that it's not sure, as you said (and as I think too), that free software is open-source by default and vice versa. Is it true? I have no examples (others than NASA Open Source Agreement) to prove that. Nov 28 '14 at 21:25
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    "that free software is open-source by default and vice versa" - I never said about vice versa, FSF and OSI have different requirements for approving licenses. You can see matrix of licenses here en.wikipedia.org/wiki/… and simular discussion here programmers.stackexchange.com/questions/21907/… - NASA license as example again. Also good reading gnu.org/philosophy/free-software-for-freedom.html
    – kirill-a
    Nov 29 '14 at 16:08
  • Sorry for the confusion. Thank you very much for the pages you linked; I will read them carefully. Nov 29 '14 at 21:35

Free software and Open source software are essentially equivalent terms. I'm not aware of any significant difference between them. Open source software was introduced as a rebranding exercise. It was designed as a more corporate-friendly term, as the term "Free" makes corporations shudder, presumably. The idea is to emphasize the viewpoint that free software constitutes a superior methodology for software development, as opposed to traditional closed/proprietary software development practices. Whether this is true or not is debatable, of course. Simultaneously, the "open source" term seeks to de-emphasize the notion that software development and distribution have an ethical component, something that was central to the term "free software". People like Eric Raymond and Bruce Perens were behind this rebranding.

However, the two definitions are essentially equivalent as operational criteria. I.e. if software is considered acceptable under one definition, in the overwhelming majority of cases it will be consided acceptable under the other. In fact, I am not aware of any counterexamples. In part this is because Bruce Perens was instrumental in framing the Debian Free Software Guidelines during his tenure as Debian Project Leader, and also made use of these criteria when creating the Open Source Definition.

The term "Free and Open Source Software" (FOSS) recognises this equivalence by grouping the two terms together into an umbrella term.

Note: there are two main definitions of Free Software in use, the FSFs "Free Software Definition" and Debian's "Free Software Guidelines", and one definition of open source software, namely "Open Source Definition". These definitions are all discussed in http://en.wikipedia.org/wiki/Free_software#Definition.

  • I agree: the two definitions are practically equivalent, but not identical: "In practice, open source stands for criteria a little weaker than those of free software. As far as we know, all existing free software would qualify as open source. Nearly all open source software is free software, but there are exceptions" (gnu.org/philosophy/open-source-misses-the-point.en.html) Nov 28 '14 at 15:34
  • @user2431763 "In practice, open source stands for criteria a little weaker than those of free software." I'm willing to be educated. Counter-example, please. Nov 28 '14 at 15:46

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