In his note, Stallman made clear the difference between Free and Open Source Software (FOSS) and open source as conceived by Eric Raymond and supporters in the business community. FOSS is not just "free as in free beer". Under FOSS software is free, not just for the user. The software itself has liberties.

FOSS is an abbreviation for Free and Open Source Software. In other words, FOSS is software whose source code is openly available. People can install and even modify FOSS as they please, so long as they follow a few basic requirements listed in the license.

Hearing the terms "free software" or "open source," you might imagine that they referred to a single school of thought. Even "free and open source software" (FOSS) suggests only two different outlooks: Free software, which values political and philosophical freedom, and open source, whose main interest is enhanced software quality.

I have been pondering the meaning of “free” in association with Free Open Source Software (FOSS) in general and GNU/Linux in particular. If one asks a FOSS advocate what free means in regard to these one might hear the reply, “Free as in beer!” and/or “Free as in freedom!”.

“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...» --

The Workshop on the Future of Research on Free/Open Source Software (FOSS) was recently held in Newport Beach, California. FOSS 2010 was an invitation-only workshop aimed at identifying the key research projects and challenges for free and open source software.

The methodologies of Open Source are not owned or guided by any one person. The closest thing we have are the Open Source Initiative (OSI) and support of the Free Software Foundation (FSF). The OSI certifies what qualifies as an open source license.

Latest examples of Microsoft's strategy, wherein it sends out affiliates to pretend to be FOSS people and then promote software patent deals, separation between Open Source and Free software, departure from the GPL, promotion of "open" core (proprietary) as "Open Source", and demotion of free/libre platforms like GNU/Linux along with free suites/formats like ODF

"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.