Open source software is software where the source code is freely distributable. It's closely aligned with free software.
ESR has written a paper which are his predictions on the open source movement.
Although all free software is, by definition, open source, not all open source software is free(speech). For example, PINE, POVray, ssh, and the like are all restricted, and the source code is basically how they make binaries available for all platforms; with those programs you cannot distribute modifications on your own, and in some cases (such as PINE) you can't even distribute your own binaries. This makes things funky for Debian, where it has its own way of keeping programs consistent in configuration; to get PINE on a Debian system, you have to download the unmodified source and then patch it with the Debian modifications to build your own binary. Very annoying.

POVray isn't quite so bad. Basically you can distribute patches and unofficial binaries but you can't fork or distribute modified source code, and the POV team also likes to sit on the latest-greatest modifications in the source distribution; lately they've only been releasing binary-only Windows releases. Yuck.

The term has also been applied liberally to other things which don't properly have source code but nevertheless follow an "open" design philosophy - in other words, they allow their user community to make modifications and redistribute them.

Legal groups, medical groups, scientific research groups, role-playing games, comics, and many other sources of intellectual property have had the rubric "open source" applied to their output.

open = O = open switch

open source n.

[common; also adj. `open-source'] Term coined in March 1998 following the Mozilla release to describe software distributed in source under licenses guaranteeing anybody rights to freely use, modify, and redistribute, the code. The intent was to be able to sell the hackers' ways of doing software to industry and the mainstream by avoiding the negative connotations (to suits) of the term "free software". For discussion of the follow-on tactics and their consequences, see the Open Source Initiative site.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

The term 'open source' first arose out of a strategy session held on February 3, 1998* at Palo Alto, California, which included Todd Anderson, Chris Peterson of the Foresight Institute, Jon "Maddog" Hall and Larry Augustin of Linux International, Sam Ockman of the SVLUG, and of course, Eric S. Raymond. This session came up after Netscape's announcement that January 22 that they would be releasing the complete source code of their web browser (which later became the Mozilla project), and the group thought that the event was a precious window of opportunity for them to convince the corporate world of the superiority of an open development process.

The term that existed at the time that was used to denote this open development process that they were advocating was of course Free Software, which had been coined by the earlier Free Software Foundation and GNU Project. They felt, however, that the term 'Free software' emphasized a political ideology far too much and had a confrontational attitude that would probably cause most businesses to shy away from it, so they decided to coin a new term for it, and come up with strategies that would emphasize the effectivity of the open approach to software development as opposed to the ideology it represented. Chris Peterson thought of the name 'open source', and the rest of them decided that was the best they could come up with.

They began to spread the word afterwards, and people such as Linus Torvalds and Bruce Perens gave their enthusiastic support, with Perens offering to trademark the term and providing hosting for the website. Richard M. Stallman of the FSF initially thought of adopting the term as well, however he changed his mind and stuck to the term Free Software instead, for reasons that will be explained below. Raymond also promptly changes the text of his seminal work 'The Cathedral and the Bazaar' to read 'open source' where it used to say 'free software'. The official Netscape press release announcing the Mozilla Project on February 23 used the term 'open source', and soon after the term began appearing in trade publications, mostly with positive spin.

Soon after, around October 31, confidential memoranda from within Microsoft were leaked that detailed the giant corporation's internal analysis of this 'upstart' movement, the infamous Halloween Documents as they came to be known, and Steve Ballmer himself admitted that yes, they're worried about all of this, as it's not only diametrically opposed to their approach to software but positively inimical to it. Other large corporations such as IBM, HP, and SGI have on the other hand given enthusiastic support, with IBM even going as far as investing billions of dollars in Linux and other open source development in the coming years.

The adoption of the term Open Source Software (OSS) in lieu of the term Free Software (FS) has led to a 'schism' within the group of advocates of open software development. This is occasionally erroneously thought of in the same way as the factionalism that often erupted in radical movements of the 1960's, disagreements occur due to details of strategy (the praxis as it were), a split occurs and the factions that result begin treating each other like enemies. The opposite is true however with the OSS and FS movements: their use of different terminology has resulted in a different philosophy, value system, and a different set of basic principles.

Nonetheless the OSS and FS camps both agree on the same fundamentals with regards to software and its licensing, so perhaps in another sense OSS and FS actually do refer to the same thing. They both believe that:
  1. Software should be freely redistributable. The license for it should not prevent any party from selling or redistributing the software.
  2. The program must include source code, either the source must be distributed along with any binary, or obtainable from a well-publicized location.
  3. Licenses for the source must permit arbitrary modification for any purpose, and grant the right to redistribute such changes.
  4. If the software has been modified by someone, it should be made clear that it has been modified and who has done the modifications, if they are redistributed.
  5. Software licenses should not discriminate against any individuals or groups of individuals or specific fields of endeavor, e.g. saying that a software package is 'free for non-commercial use' is totally unacceptable.
  6. The license must also apply to anyone to whom the software has been distributed, and should not be dependent on where the software has been obtained (i.e. a program cannot have different licenses if it were obtained standalone and obtained as part of a collection of software). It should also not attempt to influence the licensing of other packages that have been distributed along with it.**

Their agreement on these important matters has allowed them to coexist peacefully and even cooperate on projects. Both the OSS and FS camp have used these general principles to evaluate various software licenses, and they almost always agree on whether a license is acceptable, with some exceptions (most notably the APSL, which OSS accepts but FS rejects), that seem to reflect their differences in principle.

However, the OSS camp has tried to focus more on the practical benefits this approach to software development gives, the rapid and efficient pace of coding and testing, the ability to collect expertise from communities of hackers all over the world, and so forth. They tout the strong reliability and stability of open source software compared to the fragile and crash-prone monstrosities of proprietary software, of which Microsoft software is the most often given example. This practical approach has been responsible for the success of the movement in encouraging the spread and use of open source among large corporations.

The FS camp on the other hand has consistently sought to emphasize the freedom that this approach to software development gives, and they believe in the principles of software given above as inalienable rights everyone should have, and should be valued for their own sake, over and above the convenience it gives. This view is considered by the OSS camp as being 'too extreme', and they feel that overemphasizing it is counterproductive to the cause, though many of them value these principles at least as much as the adherents of FS. The OSS camp merely chooses not to emphasize it too much.

* See the Free software and open source software nodes for times earlier than this.

** The GNU General Public License fulfills this requirement, as it only influences other programs that specifically take GPLed code to form a larger work.


History of OSS

The Open Source Software movement both created and was born from the origins of the Internet. The first section of this writeup will detail the history of OSS, looking at deep roots in the origin of the Internet. The second section deals with characteristics of open source, and the third with connections between open source and the digital divide.

Early days of the Internet

In many ways, the birth of the OSS movement is tied inextricably to the birth of the computer network, starting with ARPAnet. It was this type of communication tool that allowed mathematicians (the original programmers) and computer scientists to share information in a way beyond “distinct from” the postal service.

In the time period in which the foundations for what would become the Internet were laid, software was shared freely. There were a few reasons why this was possible. One was that software existed solely in an academic realm, with support from defense budgets. This was not inevitable “a random happening”, but a design decision of J.C.R Licklider at the Advance Research Projects Administration (ARPA) Information Processing Techniques Office (IPTO). He wanted the computer network developed in the culture of academia, rather than in defense, to avoid some of the bureaucracies of the military-industrial complex. Through the auspices of Licklider, the IPTO funded such endeavors as Project MAC, which provided research funding to MIT which laid ground for the time-sharing computing explosion in that area. Another fateful project funded by the IPTO was the Augmentation Research Center (ARC) at the Stanford Research Institute (SRI). ARC, head by Douglas Engelbart, created several revolutionary computing ideas such as electronic mail, word processing, the mouse as an input device, windowing environments and hypertext.

An entire history of this area is beyond the scope of this writeup, and is covered in other texts . The importance of this history to the topic at hand is the birth of computer mediated communication software out of the university setting, where a long history of academic sharing meant that software was traded between computing centers freely. Software was seen as the result of research, as well as tools for research, and both were traditionally shared openly in academia.

It was academic research, funded with public money, that created the free, open tools that became the Internet. Vint Cerf and Bob Kahn were hired to help create the first Internet Protocols. Bob Metcalfe was funded by ARPA when he came up with Ethernet. All protocols and software was carefully stored and made available. The code was included in RFC’s (Request For Comments) which were documents available on the Net to collect bug findings, patches and so forth.

This openness was crucial for early adoption of ARPAnet and the extension of early computer networks. By openly sharing protocols, software and standards, universities could be saved from the cost of developing these layers each time they wanted to be part of the network. That cost savings lowered the barrier to entry for universities to participate in the growing computer network.


UNIX also has a role in this early history of open source software. UNIX was developed in the early 1970’s using the C language, which was being developed in parallel to the operating system. It was the first time a computer OS was not tied specifically to the hardware it would run on. UNIX, like all software at the time, was freely available.

However, the original UNIX, which was developed at Berkeley, soon splintered as hardware manufacturers developed proprietary versions of UNIX to increase customer lock-in. It was this closing that would eventually lead to the need of OSS alternatives like GNU, BSD and Linux.

Rainy Days: The Closing of the Internet

In the late 1980’s, the Department of Defense took responsibility of the ARPAnet when the National Science Foundation no longer wanted it. Defense workers moved to using the tools developed on the ARPAnet, like email and ftp, but soon found that the “open” attitude of the academic researchers did not rest well with the secrecy needs of a military organization. Academic researchers, for their part, did not appreciate that their free territory suddenly had fences installed by relative newcomers.

To address these issues, ARPAnet was split off and reserved for defense use only, and the academic portions were renamed “the Internet”. However, this is also the time that the government decide to extend membership of the Internet to the private sector. Private companies had always had a role in the Internet, but now the scale was vastly increased. The private sector, like the military sector, soon found that absolute openness did not suit their needs like it did for academics. Information soon became closed, and for-profit software shops claimed copyright and patent protection for their materials. Actually, this was not a new concept in general. Similar protection of information had been done by Microsoft and AT&T in the 1970’s, but the Net had remained largely free of such controls. This was changing.

Richard Stallman and the Free Software Foundation

In the early 1980’s, in the cauldron of splintered UNIX licenses, NSF moving out of the ARPAnet, and rising software companies, Richard Stallman appeared. A programmer who had worked on many of the pieces of software on the early Net instantiations while at MIT’s AI lab, Stallman recollects being shocked the first time he asked for source code on the Net and was refused. This was a significant shift in the 15 year history of network development, and was a significant moment for the programmer.

In reaction to this new attitude towards software, Stallman established the Free Software Foundation (FSF). The term “free” here is further defined by the axiomatic “Free as in speech, not as in beer.” The FSF was the first cohesive voice for those programmers who had made a habit of creating software that they made publicly available, and was seen as a necessary response to the voices of private companies claiming copyright protections.

The FSF created several tools important to the open source movement, including Emacs, a text editing program, but of particular import here is the GNU Public License (GPL), also known as copyleft. Open source licenses are covered in more detail below, but the GPL had several significant pieces that were contrary to common copyright laws. For example, in the GPL:

  • Software under the GPL cannot be “closed” i.e. you cannot take the code and claim copyright on it.
  • Any software using a portion of GPL software is also under the requirements of the GPL.
  • The author of the software must be attributed at all times.
Stallman and the FSF remain active and important in the open source world, though many main stream open source developers consider them too anti-commercial and zealous about their mission. Programmers revolting against the strict openness of the GPL have created alternative licenses that are not so demanding about future development.


In 1991, a new model of shared software development, different than the model pushed by the FSF, arose from the work of a grad student in Finland. A message went out on the comp.os.minix newsgroup on October 5, 1991:

Do you pine for the nice days of Minix-1.1, when men were men and wrote their own device drivers? Are you without a nice project and are just dying to cut your teeth on an OS you can try to modify for your needs? Are you finding it frustrating when everything works on Minix? No more all-nighters to get a nifty program working? Then this post might be just for you.

As I mentioned a month ago, I’m working on a free version of a Minix-look-alike for AT-386 computers. It has finally reached a stage where it’s even usable (though may not be, depending on what you want), and I am willing to put out the sources for wider distribution This is a program for hackers by a hacker. I’ve enjoyed doing it, and somebody might enjoy looking at it and even modifying it for their own needs. It is still small enough to understand, use and modify, and I am looking forward to any comments you might have. I’m also interested in hearing from anybody who has written any of the utilities/library functions for minix. If your efforts are freely distributable (under copyright or even public domain), I’d like to hear from you, so I can add them to the system.

This innocuous message was to receive quite the response. Linus Torvalds initially called his UNIX derivative “Freax”, as in Free+Unix, but was persuaded to change it to Linux. Of the first ten people who downloaded Linux, five sent back code to improve the software .

Soon, a new method of developing software projects developed, mostly encapsulated by this original message from Torvalds. People would send him, and soon a few trusted colleagues, code to improve Linux, and Torvalds would decide whether or not to add that code to the Linux kernel. Release 1.0 was made available in 1994. Currently, close to ten years after this original message, there are more than three million lines of code in the software, donated by hackers, and between 4 and 7 million users .

Even for open source projects, Linux was something new. This kind of distributed, open development process stood in stark contrast to the closed, secretive development processes of commercial software shops, and even university labs. It was one thing to build something and allow the code to be tinkered with, but quite another to build something major, like an operating system, using the efforts of hundreds of developers all over the world.

This new paradigm for software production attracted the attention of Eric S. Raymond. Raymond was the developer of an open source program called Sendmail, and had long been interested in the culture of the hackers. He wrote several influential pieces drawing together the ethos of this community, most notably “The Hacker’s Dictionary” . Raymond observed the success of the Linux developers in creating a cheap, portable, stable version of UNIX, and codified what we saw as the differences in development between this and traditional, closed shop types of development. These observations were codified in “The Cathedral and the Bazaar” , which remains an important introduction to how open source projects develop and operate.

The World Wide Web and Netscape

Almost paradoxically, Netscape has helped and hindered the OSS movement. The first Web browser, Mosaic, was developed at University of Illinois Champaign-Urbana at the National Center for Supercomputing Applications (NCSA). It was government endorsed, and open. Netscape, founded in part by people who had worked on developing the Mosaic browser, set out to deliberately create an alternative to Mosaic, which they named Mozilla (Mosaic-Killer).

Not only did they manage to create this closed version of an open browser, but Netscape then ignored the University of Illinois Champaign-Urbana’s demands for royalties and flooded the Internet with free versions of their software. Effectively, they undercut university control of an open browser standard and replaced it with something proprietary and closed. The U.S. government could have pursued legal action but did not. Champaign-Urbana, lacking support from the U.S. Prosecutor’s office dropped their suit as well, and Netscape succeeded in commercializing the Web.

In January of 1998, Netscape announced they were going to open the source code for the new Netscape browser software, and invited the open source community to participate in its development. Pressure from Microsoft’s Internet Explorer had the Netscape management looking for a way to compete against the software giant, and quoted “The Cathedral and the Bazaar” as inspiration for the decision.

Open Source In 1998

Netscape’s decision to open its source code caused a significant chain of events. The decision was announced in January 1998. In February 1998, Eric Raymond consulted with Netscape on how best to organize their efforts. It was there that he decided that the free software movement was in danger of obsolescence, or at least serious delay, if it continued to distance itself from the commercial sector. The term “free” with its mixed connotations was hobbling the movement.

A meeting of leaders of the Free Software movement on March 7, 1998 convened to discuss the future of the movement. They determined, with the exception of Stallman, that free software as a term had to be abandoned, and the term “open source” was recommended instead.

At the same meeting, a program of memetic engineering was also established. There were already some infrastructure pieces in place, like Slashdot, Freshmeat and Sourceforge, but the newly crafted Open Source Initiative wanted to extend the conversation into the public sphere. By the end of April 1998, articles on “Open Source” appeared in the Economist, the New York Times and Salon, as well as many of the technical journals.

A watershed moment for the new Open Source movement happened in October of 1998 when Raymond released “The Halloween Documents” which were internal Microsoft memoranda outlining the potential threat of open source to the software giant. Open source had arrived.

Ethics of OSS

Open Source vs. Free Software

The Open Source Initiative and the Free Software Foundation have an ambivalent relationship as they both act as proponents of similar ideas. Richard Stallman of the FSF feels that the term “Open Source” betrays the nature of the free software movement.

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