How to Use GNU Licenses for Your Own Software| www.gnu.org
What is Copyleft?| www.gnu.org
Why the Affero GPL| www.gnu.org
Who Does That Server Really Serve?| www.gnu.org
Read this page in Spanish.| www.fsf.org
What does “GPL” stand for?| www.gnu.org
GNU General Public License (GPL) version 3| www.gnu.org
Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use.| www.gnu.org