GPL3

GPL3 is the third version of the GNU General Public License, a free software license published by the Free Software Foundation (FSF) in 2007. It grants users the rights to run, study, modify, and distribute software, while requiring that redistributed derivative works remain under the same license terms.

Key features include a strong copyleft requirement, meaning that modified and redistributed versions must carry the same licensing terms. The license requires that source code be made available with executable distributions, and it adds protections against hardware restrictions that block user modifications (tivoization). It also provides an explicit patent license from contributors to users and includes a patent retaliation clause: if a contributor sues for patent infringement over the licensed software, their rights under the license can be terminated for the user. GPLv3 allows distributing software under GPLv3 or any later version, provided the distribution specifies the appropriate versioning option, which affects compatibility with other licenses.

GPLv3 is not fully backward compatible with GPLv2-only code; combining such code typically requires relicense or dual-licensing. The license was designed to be more internationally clear, address legal ambiguities, and better counter large-system and device-level restrictions. Some existing free software projects have adopted GPLv3, while others continue to use GPLv2-only.

Impact and reception have been mixed: supporters view GPLv3 as strengthening users' freedoms and patent protections; critics argue that its terms can complicate integration with some licenses and hardware ecosystems. Overall, GPLv3 remains a cornerstone of the GNU licenses and a key reference point in discussions about software freedom and copyleft.