From Liz Laffan’s “GPLv2 vs GPLv3: The two seminal open source licenses, their roots, consequences and repercussions” (VisionMobile: September 2007):
From a licensing perspective, the vast majority (typically 60-70%) of all open source projects are licensed under the GNU Public License version 2 (GPLv2).
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GPLv3 was published in July 2007, some 16 years following the creation of GPLv2. The purpose of this new license is to address some of the areas identified for improvement and clarification in GPLv2 – such as patent indemnity, internationalisation and remedies for inadvertent license infringement (rather than the previous immediate termination effect). The new GPLv3 license is nearly double the length of the GPLv2 …
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GPLv3 differs to GPLv2 in several important ways. Firstly it provides more clarity on patent licenses and attempts to clarify what is meant by both a distribution and derivative works. Secondly it revokes the immediate termination of license clause in favour of licensee opportunities to ‘fix’ any violations within a given time-period. In addition there are explicit ‘Additional Terms’ which permits users to choose from a fixed set of alternative terms which can modify the standard GPLv3 terms. These are all welcome, positive moves which should benefit all users of the GPLv3 license.
Nonetheless there are three contentious aspects of GPLv3 that have provoked much discussion in the FOSS community and could deter adoption of GPLv3 by more circumspect users and organisations.