21 GNU General Public License

Explore the website at https://www.gnu.org/copyleft/gpl.html


GPL or GNU General Public License was the first copyleft license, and is still the most broadly used.

Key Points

  • Free, copyleft license for software + other things
  • To preserve, not take away your freedom
    • the right to distribute software, even at a cost
    • The right to receive the source code and make changes
  • Rules
    • Need to respect the freedom of others by informing them they can access the source code.
    • assert copyright and then offer people the GNU license
  • Another version of the GPL called the AGPL. You have to distribute source code, even if you don’t distribute the software as in the case of  web apps (e.g. facebook)

Discussion Questions

  1. What is the situation with devices that don’t let users run modified version in the 3rd to last paragraph?
  2. How could a patent be applied to software?
  3. It’s interesting that GPL licensed  software can be used to create proprietary software. Is this for practical reasons?
  4. Microsoft seems to claim that GPL has some viral properties, does non-free software not have these same properties?
  5. How can Stallman justify selling license exceptions to companies? Aren’t they evil?

Additional Resources


An Open Education Reader Copyright © 2014 by David Wiley is licensed under a Ontario Commons License – No Derivatives, except where otherwise noted.

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