The English word "free" is unfortunately very ambiguous, which is a problem that proponents of "free software" have to wrestle with almost continually. "Free" has two main meanings, both of which can apply to "free software:"
Free of cost (the French "gratuit")
Those that are new to "GNU Public License" software first think of this aspect. If you don't have to pay for something, many consumers are quite happy. In contrast, corporate users are concerned by the lack of cost, as it suggests to them a lack of support and a lack of value.
Free of restrictions (the French "libre," which roughly corresponds to the English word "liberty")
To developers that wish to create derivative works, this aspect is far more important. While the software may be "free of charge," if you are not at liberty to use it as you wish, then it lacks this critical aspect of freedom.
The "catchy" way that this is often referred to is to say: " It's like 'free speech,' not 'free beer.' "
It must be noted that having complete and utter freedom is not something that is particularly tenable, at least not within the context of modern intellectual property law. The nearest thing to "utter" freedom would be to place works "in the public domain." Unfortunately, the legal consequence of placing works "in the public domain" is that someone may often pick them up and treat them as their own proprietary property, thus completely restricting access to the work.
It thus proves necessary to have some form of intellectual property license that applies some minimal set of restrictions so as to try to maximize peoples' ability to "freely" use the works.
Different people have come up with different such sets of restrictions. There is unfortunately a good deal of disagreement as to which approach is preferable. The two most common licenses for "free software" are the GNU Public License and the BSD License. There is some conflict over which is "more free."
It appears that it is appropriate to have some different arrangement for things that are read by humans as compared to things read and interpreted by computers. Neither the "laissez-faire" approach of the BSD License nor then "differently-restrictive" approach of the GPL appears to be perfectly appropriate for literature or documentation. The GNU Free Documentation License is being proposed as an alternative. The other literary license that has considerable popularity is the OpenContent License.
The earliest references to "free" software that start presenting a coherent "philosophy" of free software can be found in Richard Stallman's The GNU Manifesto. The Free Software Foundation web site contains a number of documents presenting their views.
Inspiration for ideas in this essay can be traced back to Eric Raymond's The Cathedral and the Bazaar essay. Both Eric Raymond's "Cathedral/Bazaar" paper and this one were cited in Technology News from Wired News in connection with the reports that Netscape Communications Corp were to make sources to Netscape Navigator/Communicator freely available under a license similar to the GNU Public License. Eric's writings also include an essay on the Economics of Open Source Software, as well as Homesteading the Noosphere: An Introductory Contradiction
Francois Rene Rideau has written an article providing some evaluation of Eric Raymond's papers. He disagrees with some of Eric's points, and has some interesting thoughts.
This paper was cited in the article The Main Thing: Software Development for the Greater Good written by the president of the Netscape Communications Corporation.
As a result of Eric Raymond's discussions with Netscape about how they might most appropriately deal with licenses like the GNU Public License, a group of advocates has come up with the proposal that the new term "open source" be used rather than "free software" to more readily draw corporate interest.
Larry Wall's Uncultured Perl comments on Eric Raymond's thesis thus:
Now let me just say that I think cathedrals have gotten a bum rap lately. Open Source advocate Eric Raymond has likened the commercial software development model to a cathedral, while he compares free software development to a bazaar.
Eric's heart is in the right place, but I think his metaphors are a little off. Most cathedrals were built in plain view with lots of volunteer labor. And most of the bazaars I've seen have produced little of lasting architectural value. Eric should have written about artists who insist on having an unveiling when their sculpture or painting is finished. Somehow I can't imagine anyone pulling a shroud off of a cathedral and saying, "Voila!"
This paper was translated into French, and very nicely, to my reading of it. Linux et le developpement decentralise.
Freely Redistributable Software in Business is a page that references many of the recent developments in "libre" software.
Which bears a marked resemblance to my Your Fair Share document. It would be very interesting if there's no inspiration from my document...
Note that with many of the "arguably not free" licenses, the issue is not one of what the authors of the software "owe" to the community. It is rather of what conditions are needed for developers of free software to consider the code to be "safe" to invest their time in it.
For instance, it is well and fine that Apple offers the ability to look at "Darwin" code without charge. But if their license restrictions mean that things I develop in conjunction with that code wind up not being "free" for me to use, or to pass on to others under terms I find acceptable, then I will find it unacceptable to invest my time writing code connected with Darwin.
There are some people, particularly some of the more "strident" supporters of BSD-related software, that find the restrictions of the GPL unacceptable. Their finding it unacceptable for their purposes is a reasonable preference. The "flame wars" wherein they fight with some of the insanely strident GPL supporters, who find the same restrictions acceptable, and find the restrictions involved in BSD licenses unacceptable tend to miss the point that they're not talking about global absolutes of what is, or is not, universally acceptable or unacceptable, but rather personal preferences.
Free Software is dead; long live "Open Source" by Eric Raymond, and
The FSF "Alpha" Site at ftp://alpha.gnu.org/pub/gnu/
This site contains "alpha" editions of GNU software. People are encouraged not to redistribute this stuff simply because it's not yet ready for "official" release as stable software.
AbiSource Public License (AbiPL) - Intended to be compatible with the Mozilla Public License
Note that the latest news is that the AbiPL has apparently been scrapped in favor of the GPL...
Discussing the licensing issues with the new Plan 9 license, where the "freeness" may be argued both ways...
LinuxToday published an assessment by Richard Stallman that describes a number of the license provisions as "obnoxious."
Mozilla is trebly licensed under:
The "Mozilla Public License," which allows the folks at Mozilla/Netscape/AOL to use it However They Will;
The GPL, allowing it to be integrated with other GPLed code;
The LGPL, allowing it to be integrated into possibly-proprietary software.
It starts with the wise counsel "Figure out what your goals are first."
Report on nonfree software installed on a Debian system. A future version may provide quotes from RMS moralizing on why you should deinstall the nonfree software...
The Weapon of Openness is a Libertarian essay on Open Source.