Open source vs free software: what's the difference?
February 2018 marked the 20th anniversary of the official recognition of open source software. However, the debate regarding the differences, if any, between 'open source' and 'free' software continues unabated.
Richard Stallman, who is credited with developing the concept of 'free software' in the 1980s, says the term 'free software' has nothing to do with cost. For him, free software is a social movement, a philosophy, while open source is a development methodology.
Not the same as free beer
"When we call software 'free', we mean that it respects the users' essential freedoms: the freedom to run it, to study and change it, and to redistribute copies with or without changes. This is a matter of freedom, not price, so think of 'free speech', not 'free beer'," he wrote in his seminal essay, 'Why Open Source misses the point of Free Software'.
According to Stallman, the free software movement started campaigning for computer users' freedom in 1983. In 1984, the free operating system, GNU, was launched, followed by the development of the GNU General Public Licence, to enable subscribers to the free software philosophy to avoid so-called non-free operating systems.
Some 14 years later, disagreement over the goals and underlying philosophy of the free software movement led to the emergence of open source.
Open source essential freedoms
In an article posted on Opensource.com, Scott Peterson, a member of the Red Hat legal team, explained that, in order to be considered 'free', a software program must comply with four 'essential freedoms'.
The Free Software Foundation (FSF) defines these as:
- The freedom to run the program as you wish, for any purpose;
- The freedom to study how the program works and change it so it does your computing as you wish. Access to the source code is a precondition for this;
- The freedom to redistribute copies so you can help your neighbour; and
- The freedom to distribute copies of your modified versions to others. Access to the source code is a precondition for this.
Two of these freedoms recognise what is widely regarded as an essential component of open source software - access to source code.
However, the Open Source Foundation (OSF) emphasises that open source doesn't just mean access to the source code. Indeed, the OSF definition of open source software has no fewer than 10 criteria that must be satisfied:
- free redistribution;
- access to the source code;
- the acceptance of modifications and derived works;
- protection of the integrity of the author's source code;
- no discrimination against persons or groups;
- no discrimination against fields of endeavour;
- distribution of licence;
- the licence must not be specific to a product;
- nor must it restrict other software; and
- it must be technology neutral.
Therefore, it's the underlying set of values that differentiate free and open source software, Petersen says. Free software's focus is on what the recipient of the software is permitted to do with it, while open source focuses on the "practical consequences enabled by these licences, including effective collaboration on software development".
Peterson maintains that these two concepts are not mutually exclusive and that there is no need for an either/or approach. "Many people find varying degrees of resonance with the values underlying each term," he says.
But with no value-neutral term that has gained widespread acceptance, confusion about what is free and what is open source is likely to continue for the foreseeable future.