Free software and its acronyms
GPL stands for General Public Licence. There are many kinds of GPL used in free software projects, but "free" is easily misunderstood: in this context, the term is a matter of liberty, not price. It is "free" as in "free speech" – not as in "free beer."
The principle is that users have the freedom to run, study, copy and improve free software. You can charge for the copies you distribute – but any re-distributor must provide the full source code free of charge and a copy of the full licence text.
Free software should not be confused with "freeware," which is made available free of charge – but which cannot necessarily be copied, modified and redistributed without breaching licence conditions.
It is more forgivable to confuse "free software" with "open source software", a term that comes from the late 1990s, because the differences are subtle. Proponents of each will collaborate on projects, united by a mutual hatred of proprietary software. The fundamental difference between free and open source is in values. It is said that open source is a development methodology – i.e. a job may be done better and faster by collaboration; while free software has been compared to a social movement. (The differences are explained fully at gnu.org).
The GNU GPL is by far the most popular GPL, currently underpinning more than 28,000 free software projects, or 67% of all projects, according to freshmeat.net. Its best known uses are in the Linux operating system kernel and in MySQL, the dominant database management software.
The GNU GPL was first released in 1989. It was written by Richard M Stallman, founder of the GNU Project – which developed a free UNIX-like operating system called GNU. Stallman's site explains that GNU, pronounced "guh-noo," is a recursive acronym for "GNU's Not Unix."
Stallman also founded the Free Software Foundation, or FSF, in 1985. It is a non-profit group dedicated to the promotion of free software. It released version 2 of the GNU GPL in 1991.
Variants of the GNU operating system which use the Linux kernel are now widely used. These systems are usually referred to as Linux systems; but Stallman points out that they are more accurately called GNU/Linux systems. All of them use version 2 of the GNU GPL.
The FSF is now seeking comment on its draft Version 3, or GNU GPLv3.
The GPLv3 draft
The new GPLv3 is almost twice as long as GPLv2, running to 4,500 words and 11 pages. But like its predecessor, it is easy to read by comparison to many proprietary software licences. A new version was called for, according to the FSF, because "today's environment is more complex and diverse" than the environment of 1991.
The key principle of what Stallman calls "copyleft" remains intact: make a work free and require all modified versions to be free as well. It does not mean abandoning copyright in a work; it simply places generous conditions on the use of a work.
As before, there is no warranty with GPL-based software but you have the freedom to distribute copies of it and you can charge for that service if you wish. You just have to share. "You must license the entire modified work, as a whole, under this License to anyone who comes into possession of a copy," explains clause 5 of GPLv3.
The patent provision
GPLv3 gives you unlimited permission to privately modify and run a program that is subject to the GPL – "provided you do not bring suit for patent infringement against anyone for making, using or distributing their own works based on the Program."
"Software patents threaten every free software project," explains the FSF in a 21-page note on the rationale behind the changes (there is also a helpful 16-page guide to the revision process).
Patents were addressed in GPLv2 but GPLv3 tightens the provisions.
"GPLv3 provides an explicit patent license covering any patents held by the program's developers, replacing the implicit licence on which GPLv2 relies," explains the FSF's note. "GPLv3 also implements a narrow scheme of patent retaliation against those who undertake this precise form of aggression."
Accordingly, if you bring a patent infringement lawsuit against anyone for activities relating to a work based on the program, your right to modify and run the program is terminated.
The DRM provision
The FSF reasons that "the adoption of DRM is fundamentally at odds with the spirit of the free software movement." It compares DRM-protected software to "a prison in which users can be put to deprive them of the rights that the law would otherwise allow them." The FSF aims to abolish the use of DRM. "Anything less than complete victory," it argues, "leaves the freedom of software in grave peril."
Accordingly, the software covered by the GPL must neither be subject to, nor subject other works to, digital restrictions from which escape is forbidden. Clause 3 states, "no permission is given to redistribute covered works that illegally invade users' privacy, nor for modes of distribution that deny users that run covered works the full exercise of the legal rights granted by this License."
"No covered work constitutes part of an effective technological protection measure: that is to say, distribution of a covered work as part of a system to generate or access certain data constitutes general permission at least for development, distribution and use, under this License, of other software capable of accessing the same data."
Linux and GPLv3
It is expected that the Linux kernel will continue to be licensed under GPLv2, even after GPLv3 is finalised. This is because its licence terms require improvements to be licensed under GPLv2 exclusively – as opposed to the more common provision of requiring improvements of GPL software under "GPLv2 or later".
The final version of GPLv3 will not be ready this year. The FSF is giving itself until March 2007. But it seeks comments now in the hope of releasing a second draft version in June and a possible third draft in October.