The GNU General Public License Version 2, released in June 1991, is the most widely deployed free software license in history. The event release-of-gpl-v2 sits at the heart of the founding-gnu-and-fsf-1983-1991 era. When linus-torvalds chose GPL v2 for the Linux kernel in 1992, he applied this license to software that would eventually run on hundreds of millions of devices — making GPL v2 the legal foundation of the Linux ecosystem and the entire gpl-and-linux-era-1991-1998.
GPL v2 introduced two significant additions beyond gpl-v1. The first was the "Liberty or Death" clause (section 7): if external conditions — such as patents, court orders, or contractual obligations — prevent a distributor from complying with the GPL's requirements, they may not distribute the software at all. This clause reflected growing concern about software patents and their potential to weaponize GPL-licensed code against distributors. The second addition tightened the "distribution" requirements to close gaps that had emerged in practice.
The preamble of GPL v2 contains stallman's most memorable formulation: "When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new programs; and that you know you can do these things." This libre-vs-gratis distinction became the foundational talking point of the free-software-foundation.
The "only version 2" language that linus-torvalds used when licensing Linux — "GPL version 2, only" rather than "version 2 or later" — would later become a significant complication. When stallman and eben-moglen developed gpl-v3 to address tivoization and patents, Torvalds refused to relicense Linux to GPL v3, creating a permanent split in the copyleft ecosystem. The Linux kernel remains under GPL v2-only.
GPL v2's dominance is not merely historical. As of the mid-2020s, GPL v2 (often in combination with a "or later" clause) governs more active open source projects than any other license. Its copyleft mechanism has been litigated and upheld in courts in the United States and Germany, establishing that the GPL is an enforceable contract. eben-moglen and the software-freedom-law-center, and later the software-freedom-conservancy, have pursued enforcement actions that established key precedents.
The open-source-definition-schism of 1998, in which eric-raymond, bruce-perens, and tim-oreilly helped found the open-source-initiative, was partly a response to what they saw as the ideological freight of the GPL and its copyleft requirements. GPL v2 is the specific document they were responding to, and its terms — particularly the requirement that derivatives be licensed under the same terms — are what the open source camp sometimes characterized as "viral" or "infectious."