Open source or open source software, sometimes abbreviated OSS, means any computer software whose source code is either in the public domain or, more commonly, is copyrighted by one or more persons/entities and distributed under an open-source license such as the GNU General Public License (GPL) (This particular license is often refered to as a copyleft). Such a license may require that the source code be distributed along with the software, and that the source code be freely modifiable, with at most minor restrictions, such as a requirement to preserve the authors' names and copyright statement in the code. In some cases, as with Apache or FreeBSD, there are only very minor conditions on use of modified versions. When used as an adjective, the term is hyphenated, e.g. "Apache is open-source software." One common form of open source software uses the OSI Open Source Definition.
These are rights for users of the software. An open-source license itself does not necessarily require that the software, or its source, initially has to be freely (in both senses of the word) available on the Internet. Most popular open-source software is, however.
The term open source in common usage may also refer to any software with publicly available source code, regardless of its license, but this usage provokes strong disapproval from the OSF open source community, which may call them "disclosed source" rather than open source. Examples of such non-OSF open source software include some versions of Solaris and PGP. There are also shared source licenses which, on the surface, appear to be open source, but have critical differences.
"Open Source" and "Free Software"
The term "Open Source" is distinct from "free software". Software that fits the Free Software Foundation's (FSF) very similar Free software definition, and was developed to support the motivations of the free software movement, may be more appropriately called free software. The GNU project in particular objects to their works being referred to as "open source" or "Open Source".
The decision to adopt the term "open source", suggested by Christine Peterson of the Foresight Institute, was based partly on the confusion caused by the dual meaning of the word "free"; the FSF intended the word to mean "free as in free speech", not "free as in free beer", but nevertheless, free software came to be associated with zero cost, a problem which was exacerbated by the fact that a great deal of it is, in fact, free of charge. It was hoped that the usage of the newer term "open source" would eliminate such ambiguity, and would also be easier to "market" to business users (who might mistakenly associate "free software" with anti-commercialism). Since its introduction, however, the "open source" label has been criticized for fostering an ambiguity of a different kind: that of confusing it for mere availability of the source, rather than the freedom to use, modify, and redistribute it.
The Free Software Definition is more restrictive than the Open Source Definition; as a consequence of this, free software is open source, but open-source software may or may not be "free." In practice, nearly all open-source licenses also satisfy the FSF's free software definition, and the difference is more a matter of philosophical emphasis. (One exception is an early version of the Apple Public Source License, which was considered open-source but not free, because it did not allow private modified versions; this restriction was later removed.) Software distributed under both the GPL and BSD licenses is considered both free and open-source. The original BSD License had terms legally incompatible with the GPL, but this practical difficulty is a separate issue. Confusion about the distinctions between free and open-source software is a source of some misunderstanding, particularly in the mass media where the two terms are often applied interchangeably.
The open source movement
The open source movement is a large movement of programmers and other computer users that advocates unrestricted access to the source code of software. It grew out of licenses such as BSD, the ubiquitous access to Unix source code at universities and goals which differ somewhat from those of the Free software movement. The line between the two is somewhat blurry; both are founded in the hacker culture. Mostly, the Free software movement is based upon political and philosophical ideals, while open source proponents tend to focus on more pragmatic arguments. Openness is a term that has evolved now to refer to projects that are open to anyone and everyone to contribute to, before and/or after the actual programming. Both groups assert that this more open style of licensing allows for a superior software development process, and therefore that pursuing it is in line with rational self-interest. Free software advocates, however, would argue that "freedom" is a paramount merit that one should prefer (or at least weigh heavily) even in cases where proprietary software has some superior technical features.
Proponents of the open source development methodology claim that it is superior in a number of ways to the closed source method (and some individuals may suggest that the open source methodology is the methodology that is able to produce the quality of software that can be higher than that produced by any other methodology or technique). Stability, reliability, and security are frequently cited as reasons to support open source. One successful application of the open source model is the Linux operating system, which is renowned for its stability and security characteristics. Among the works that explore and justify open source development is a series of works by Eric S. Raymond which includes The Cathedral and the Bazaar and Homesteading the Noosphere.
Open source advocates point out that as of the early 2000s, at least 90 percent of computer programmers are employed not to produce software for direct sale, but rather to design and customize software for other purposes, such as in-house applications. According to advocates, this statistic implies that the value of software lies primarily in its usefulness to the developer or developing organization, rather than in its potential sale value, and that consequently there is usually no compelling economic reason to keep source code secret from competitors. Open-source advocates further argue that corporations frequently over-protect software in ways actually damaging to their own interests, for reasons ranging from mere institutional habit through reflexive territoriality to a rational but incorrect evaluation of the tradeoffs between collecting secrecy rent and the quality and market payoff of openness.
The open source debate
The debate over open source vs closed source (alternatively called proprietary development) is very much a religious war. While vast numbers of the current technology community members are proponents of open source, there are also people on the other side of the debate. The most obvious complaint against open source software involves intellectual property rights. Some software development companies do use the copyright and patent rights provided for software developers as their primary source of income. By keeping their software source code hidden, they can demand fees for its use. While most software is written for internal use, the fees from sale and license of commercial software is the primary source of income for companies which do sell software. Additionally, many companies with large research and development teams often develop extensive patent portfolios. These companies can charge licensing fees for the use of their patents in software, however open source distribution creates the potential for an infinite number of derived works using the patented technology with no oversight by the patent holder.
Another common argument, one that is more difficult for open source advocates to contradict with hard facts, is that closed source development allows more control over the final product. The theory behind this argument is that open source software is primarily a volunteer effort, while closed-source development is typically a salary-driven effort. By having the monetary resources to fund developers and management, and the ability to control development in a given direction, closed source proponents argue that development can be more efficient and more focused.
Large scale open-source projects such as Linux, FreeBSD, or Apache tend to discredit this argument. However, even within these very successful projects, there are often key technological components missing due to the fact that no one has the time or effort to volunteer to do them. For example, multi-threading and SMP capabilities in open-source operating systems historically (and in some cases currently) lagged behind commercial systems such as Microsoft Windows, simply because the work was not considered an interesting problem by enough qualified developers. This argument tends to hold mostly for very difficult or obscure projects with minimal immediate return, such as support for specific hardware or a long-term overhaul of system architecture. But it does not take into account the generally higher quality of such work found in the open-source projects once the work is actually undertaken. Finally, in recent years many companies, notably Apple, Red Hat and Transmeta, have begun paying full-time developers for working on open-source projects.
Open source advocates
- Bruce Perens, Eric Raymond, Linus Torvalds, Paul Vixie, Alan Cox, Tim O'Reilly, Brian Behlendorf, Russell Pavlicek (author of the book Embracing Insanity)
Projects and organizations
- Debian, FreeBSD, Mozilla, NetBSD, OpenBSD, Linux, OpenOffice.org, Open Source Initiative, OSTG, Slackware, BerliOS, SourceForge, NOSI, GNU
Examples of open source licenses
- BSD license, GNU General Public License, GNU Lesser General Public License, MIT License, Apache Software License, Mozilla Public License
For a more extensive list, see Open source license.
Examples of open source software
- Apache, Linux, BSD, Mozilla, GNU Emacs, TeX, Vim, XFree86, the GIMP, PHP, Zope, KDE, GNOME, OpenOffice.org, MySQL, Moodle, Postnuke, phpBB, GnucDNA , Shareaza
For a more extensive list, see List of open-source software packages.
- Free/Libre Open Source Software
- Open content for non-programming open source projects
- Openness the philosophic term
- Open Source Funding
- Open Source Software
- Richard Stallman is a central figure in the rival (but cooperative) free software movement, which has a significantly different philosophical basis; Stallman does not want his name associated with the term open source.
- Gift economy
- GNU Savannah
- Halloween documents
- List of open-source software packages
- Open Law project
On the creation of the name "Open Source":
- Goodbye, "free software"; hello, "open source" Raymond's announcement of the term "open source", 8 February 1998
- It's Still Free Software 16 Feb 1998, Richard Stallman. The terminology battle begins.
- "It's Time to Talk About Free Software Again" 12 months later, Bruce Perens chimes in.
- Why "Free Software" is better than "Open Source" - a later essay from FSF.
General links about open source:
- The Asian Open Source Center - has a lot of information on open source in Asia, much of it stored in a Wiki similar to Wikipedia
- A Case Against Open Source, by Mathias Strasser, 2001, from Stanford Technology Law Review
- EU-funded report on the use of open-source software
- Fundamental issues with open source software development a personal review by Michelle Levesque.
- Groklaw - Open Source Software: What Is It and How Does It Work?" - By Dr. Ben Kremer - Good general overview of open source and the GPL.
- The Institutional Design of Open Source Programming: Implications for Addressing Complex Public Policy and Management Problems
- The Open Source Alternative: Shrink-Wrap, Open Source and Copyright by Debora Halbert Ph.D., vol. 10, No. 4 (Dec. 2003) Murdoch University Electronic Journal of Law - Copyright Policy
- Open Source HealthCare Alliance
- Open Source Initiative (OSI) - a list of available licenses
- Open Sources: Voices from the Open Source Revolution - an online book containing essays from prominent members of the open source community
- W3C Open Source Software
- Collaborative Source Software- This article presents an approach to combine the best of the open source and proprietary software development worlds