GPL

Definitions

1. GNU General Public License — a copyleft license that requires any derivative work to also be released under the GPL. The 'viral' license: if your code touches GPL code, your code becomes GPL too. This is by design, not a bug.

   In plain English: A software license that says: you can use and change this code for free, but anything you build with it must also be free and open. It's 'infectious' — once in, everything connected must follow the same rules.

2. GPL v2 and GPL v3 have important differences: v3 includes an explicit patent grant and anti-tivoization clauses (preventing hardware restrictions on modified software). Linux remains GPL v2 because Linus Torvalds disagrees with v3's expanded scope. The license version matters.

   Example: 'The library is GPL v3, which means we can't use it in our proprietary product. If it were LGPL, we could link against it without the viral requirement.'

   Source: v2 vs. v3 differences

Etymology

1989

Richard Stallman publishes GPL v1, creating the first copyleft license that requires derivative works to remain open source

1991

GPL v2 releases alongside Linux, becoming the most influential open-source license in history

2007

GPL v3 adds protections against DRM and patent threats, but many major projects (Linux, MySQL) stay on v2

Related Terms

• Open Source
• MIT License
• Copyleft
• FOSS
• Apache License
• Mozilla Foundation