"...In 1998, some of the people in the free software community began using the term "open source software" instead of "free software" to describe what they do. The term "open source" quickly became associated with a different approach, a different philosophy, different values, and even a different criterion for which licenses are acceptable. The Free Software movement and the Open Source movement are today separate movements with different views and goals, although we can and do work together on some practical projects..."

RMS: «...Their stated definition for the term “open source” is somewhat broader than free software, and thus includes my work. But describing the GNU GPL as an “open source license,” as Microsoft did, is more than half misleading. The GNU GPL embodies the firm philosophy of the free software movement; it doesn't come from the open source movement.

“Open Source” advocate: «...I associate much more with the "Open Source" (also as Richard defines it) camp, and am open to the existence and use of proprietary software...» --

"Open source is a development methodology; free software is a social movement. For the free software movement, free software is an ethical imperative, because only free software respects the users' freedom. By contrast, the philosophy of open source considers issues in terms of how to make software “better”—in a practical sense only. It says that non-free software is a suboptimal solution.

It seems we mostly hear the term "Open Source" bandied about in the press. Save for the occasional references to the Free Software Foundation and FSF Europe, one might get the impression that the Free Software movement is floundering along, all but forgotten in the annals of history. In reality, though, the Free Software movement is very much alive and kicking.

"Stallman makes a clear distinction between the free software and open source movements. The free software movement is based on values of freedom and social solidarity, he said, while the open source movement is thinking about practical benefits only, and forgets what’s most important..."

"..RMS’s other mission here is to promote the Free Software Movement. The creator of the GPL...is at pains to correct misunderstandings of what the term free software means and to draw a distinction between it and the open source movement.

"...For the Open Source movement, the issue of whether software should be open source is a practical question, not an ethical one. As one person put it, “Open source is a development methodology; free software is a social movement.” For the Open Source movement, non-free software is a suboptimal solution.

In our earlier article, "Facts and Friction on Open Source and Free Software" we have explained where "Open Source" is coming from and what is its relation to Free Software and the Free Software Foundation that represents it.