GPLv3

GPLv3, the GNU General Public License version 3, is a free software license published by the Free Software Foundation (FSF) in 2007 as the successor to GPLv2. It is designed to protect software freedom by ensuring that users can run, study, share, and modify covered software. Like its predecessor, GPLv3 is a strong copyleft license, meaning that derivative works distributed in any form must also be licensed under GPLv3.

Key requirements for distribution include providing the Corresponding Source code, preserving the license text, and including notices about modifications. When distributing object code in a device or product, the distributor must also provide installation information sufficient to enable users to install and run modified versions.

Notable provisions address hardware and patents. The license prohibits tivoization by restricting embedded hardware from blocking modified software, and it includes a patent retaliation clause: if a licensee sues anyone for patent infringement on the work, their license is terminated. GPLv3 also provides patent licenses to recipients and allows "additional permissions" to be added by licensors to widen permissions. It also includes rules to promote compatibility, though GPLv3 is not automatically compatible with GPLv2-only code; projects may declare "or later" versions to enable upgrading, and there are explicit compatibility arrangements with certain licenses such as Apache 2.0 via a special exception.

Impact and usage. GPLv3 has been adopted by many free software projects and organizations seeking strong copyleft guarantees. It remains a central part of the free software licensing landscape, though it has critics who argue it can complicate linking with other licenses and commercial use.