What is Free and Open Source Software?
Free and Open Source Software (FOSS) is software which provides open rights of use, modification & distribution allowing it to be used, remixed and shared freely.
The “Free” part of FOSS does not mean that it’s monetarily without cost. This instead refers to freedoms provided to the user. These freedoms are defined as part of the Free Software Definition.
The “Open Source” part of FOSS refers to code which fits into the criteria defined by the open source definition.
It should be noted that these terms are not trademarked or owned by anyone, but their use and reputation within the software ecosystem has been built upon the above definitions and the benefits they provide.
What’s the difference between “Free” and “Open Source”?
Functionally the two a very similar, since the open source definition is derived from Debian’s free software guidelines. All free software can be considered open source. However, there is some software which may be considered open source but not free software, due to the nuance between the two definitions, although this is quite rare in practice.
The greater differences between the terms are in purpose and philosophy. Free software focuses on being a movement & campaign for the rights & freedoms of users, whereas the open source movement focuses more on practical application.
For further reading, here are some articles providing different perspectives from authors or stewards of these definitions:
- Why Open Source Misses the Point of Free Software by Richard Stallman
- History of the Open Source Initiative by the OSI
Can authors demand money for Free and Open Source software?
Sure! In fact it’s a fundamental right of both that you can charge for such software. The important factor with FOSS is that the software can be freely redistributed after purchase if there’s a fee. This means that someone can pay for the software, then share it freely among others without any required cost.
What is “Open Core”?
Open Core is a term used for projects which have a central open source core, but also provide variations & additions to that core via non-open-source code. This is often a used as a monetization approach since the non-open-source elements allow the author to retain a competitive advantage, while being able to share the core parts as open source.
There’s a wide range to the result of this approach in regard to transparency to users, and consideration to FOSS values. It can be done well where marketing & distributing of the variations is performed in a clear manner under different naming/labelling, but too often such approaches have issues when it comes to license configuration or end-user-clarity, and sometimes the open source core is severely limited and essentially treated as a demo.
What is “Source Available”?
Source Available is a common term for projects which have code available to public view. In the majority of cases, FOSS software will fit into this categorization but not always. This term is most often used to describe software which is available to access/view online, but does not fit into the definitions of Open Source or Free Software.