Aside from very specific cases, like if you work for NASA, copyright springs into existence automatically, so even assigning it to the public domain requires so

Aside from very specific cases, like if you work for NASA, copyright springs into existence automatically, so even assigning it to the public domain requires some action to divest yourself of the copyright. And even then, 'moral rights' may survive. The GPL is very much not public domain, but a license to a copyrighted work though. Which, I mean, you can read it. See 'how to apply' https://www.gnu.org/licenses/gpl-3.0.html https://www.gnu.org/licenses/gpl-3.0.html