“Free” and “open source” are two terms commonly used interchangeably in the software industry. Yet, for many developers, the difference between the two is not always clear. This can lead to confusion about how to use each source code, as well as how to make source code available for others.
The Rise of Free Software
To understand the difference between the two types of software and their licenses, one must first understand how each came into being.
In 1983, Richard Stallman founded the GNU project, with the Free Software Foundation (FSF) being founded in 1985. While the term “free software” often evokes the thought of being free in a monetary sense, the original idea was free in the sense of freedom to run, use, share, and modify the software.
As Stallman describes it, “this is a matter of freedom, not price, so think of ‘free speech,’ not ‘free beer'.”
The Open Source Movement
In 1997, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the hacker community and free software principles. This paper was one of the factors which motivated Netscape to release their popular Netscape Communicator Internet suite as free software.
This act promoted Eric Raymond and other members of the FSF to understand they need to ‘rebrand’ the FSF's social activism to make it more appealing to commercial software companies. They wanted to help corporations see the great benefits of adopting and contributing to free software.
To achieve that goal, they formed the Open Source Initiative (OSI) in 1998 to promote the creation and usages of open source software, without the hardline approach often taken by the FSF.
Where the Two Movements Are Alike
The astute reader will immediately recognize there are many similarities between the FSF and the OSI.
In fact, Richard Stallman himself acknowledged that despite philosophical differences, individuals from the two camps often work together on free, open source projects. At their core, both movements promote the use of free software that can be modified, with the underlying source freely available to all. However, the OSI takes a more pragmatic approach to increasing open source
Where the Two Movements Differ
In spite of their similarities, the philosophy and values behind it are different, as Richard Stallman describes it best with the two theoretical reactions to seeing a powerful and reliable proprietary software: A pure open source enthusiast, that is not at all influenced by the ideals of free software, will say, “Your program is very attractive. How can I get a copy?” This attitude may reward schemes that take away our freedom, leading to its loss, based on Stallman.
The free software activist will say, “Your program is very attractive, but I value my freedom more. So I reject your program. I will get my work done some other way, and support a project to develop a free replacement.”
In addition, there are two specific use cases in which the FSF differs from the Open Software Initiative, as Stallman highlighted in an article. He refers to the first example as "tivoization," or tyrant devices. These devices are named after the TiVo digital recorder that uses an executable derived from open source, but one that cannot be modified by the end-user. The second example is the Open Watcom license used for the Open Watcom C compiler. While the license meets OSI’s criteria to be considered open source, it does not meet the standard of “free” as set forth by the FSF. This is primarily due to the license requiring any changes to the source code to be published openly—even for software intended solely for private use.
Although the OSI definition of open source software is derived from the FSF’s definition for free software, it is a bit looser. In each of above cases, the tyrant devices and Open Watcom license both qualify as open source. Neither of them, however, meets the criteria set forth by the FSF, because of being closed to the end-user or by their restrictive publishing requirements.
Why it Matters
I have to admit, it usually doesn’t.
While the FSF and the OSI are primarily focused on creating free and open software—oftentimes working together toward that goal—they don’t see eye-to-eye in their approach.
While the free software fans are quick to tout their philosophy as a “purer” vision for software development and often look down on their open source counterparts, it’s important to remember one of the reasons why the OSI came into being: to aid corporations in the adoption, usage and contribution towards a larger open source software community.