I have been in the open-source community for a long time, and I am always glad to see any contribution to the literature in this research area. Many of us have thought about a unified operating system independent of hardware resources, and then Unix arrived, accompanied by the start of the GNU project based on the Linux kernel, which many of today’s Linux users accept as the standard for free (open) system projects. Although open-source initiatives started mostly within academic communities, we are witnesses to the deployment of open-source projects in business sectors, too.

Since the open-source project ecosystem is composed of many forms of licenses that allow software to be freely used, modified, and shared, it is hard to combine them into an exploratory analysis. However, Gamalielsson and Lundell successfully describe most commonly used license forms and accompanying conditions that any of the licenses define. Permissive licenses and copyleft are dominant forms within open-source project implementation, although copyleft is preferable in most open-source projects. Hence, the authors--in a short, but clear presentation of open-source licensing--describe each license form issued by various foundations and organizations working in open-source platform development. The great contribution of this study is in the descriptions of other conditions under which open-source projects could be or are developed. Related to the various national copyright laws and agreement forms, there is a need for new forms of best practices to overcome misunderstandings of fundamental copyright principles among open-source project stakeholders. It is especially important in the situation when copyleft-type licenses change existing copyright law, ensuring a project work remains freely available.

With the analysis of the most-used and known licenses, terms, and conditions from standard bodies (institutions and organizations such as the Free Software Foundation, the Open Source Initiative, the Massachusetts Institute of Technology, and the Apache Software Foundation), this study presents an excellent view into the open-source ecosystem, helping many software and project developers to better understand licensing in open/free but not always cost-free projects. Of particular interest is the authors’ presentation of exploratory data analysis that provides a valuable set of findings regarding the impact of licenses and other conditions on open software project development. Further, their findings suggest which licenses and foundations are dominant in use, as well as the conclusion that strong copyleft licensing consists of no specific conditions.

This study will be helpful reading for all involved in open-source projects; it presents an impressive contribution to the literature in open-source ecosystem research. This clear and concise presentation will help readers better understand open-source licensing definitions, deployment, and impact on the whole software community.