Open source refers generally to 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). Such a license requires 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. When used as an adjective, the term is hyphenated, i.e. "Apache is open-source software."
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 open source community. Examples of such "disclosed source" software include some versions of Solaris and PGP.
In the strict definition, the term "open source" is distinct from "free software," and it should only be applied to software that meets the terms of the Open Source Definition (see also the Free Software Foundation's (FSF) Free software definition). 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 speech, not 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 slightly 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 of the few counter-examples was an early version 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.) For instance, software distributed under both the GPL and BSD licenses are 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 from its free-ness). Confusion about the distinctions between free and open source software is the source of some misunderstanding, particularly in the mass media where the two terms are often applied interchangeably.
The open source movement is a large movement of programmers and other computer users to give easy access to computer software. It grew out of the Free software movement, and the line between the two is somewhat blurry. Mostly, the Free software movement is based upon political and philosophical ideals (sometimes referred as hacker culture), while open source proponents tend to focus on rather pragmatic matters. 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. 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 no compelling economical reason to keep source code secret from competitors.
"Open source" and "Free software"
The open source movement
Open Source advocates
Projects and Organizations
Examples of Open Source Licenses
For a more extensive list, see Open source license.Examples of Open Source Software
Related topics
See also: Halloween documents, Open Cola, SourceForge, GNU Savannah, Open Law project, Gift economy
External links