GPLv2

The GNU General Public License version 2 (GPLv2) is a free software license published by the Free Software Foundation (FSF) in 1991. It is a copyleft license intended to preserve the freedom to run, modify, and share software, by requiring that modified and redistributed versions remain under the same license.

Key provisions of GPLv2 include: when distributing binaries, the corresponding source code must be made available under GPLv2; recipients must receive the same rights to use, study, modify, and redistribute; and distributors may not impose additional restrictions beyond those in the license. The license also includes a warranty disclaimer, and an obligation to preserve copyright notices and the license terms in redistributed copies. GPLv2 does not, however, include the explicit patent grant or anti-tivoization provisions found in later versions of the license.

Variants and compatibility: projects may license code as GPLv2-only or GPLv2-or-later. The Linux kernel uses GPLv2-only, meaning it does not automatically upgrade to GPLv3. GPLv3 introduced additional protections, including explicit patent coverage and anti-tivoization measures, which are not present in GPLv2. Because of these differences, GPLv3 code is not automatically compatible with GPLv2-only code; projects often offer dual licensing (GPLv2-or-later) to facilitate broader use and compatibility.

Impact and usage: GPLv2 has been widely adopted for free software projects, particularly those seeking strong copyleft guarantees. It remains in use today, especially in software whose maintainers prefer the original terms or wish to avoid GPLv3’s new provisions, while some projects have migrated to GPLv3 or use dual licensing to balance compatibility and freedom.