GNU General Public License (GPL)

https://www.gnu.org/licenses/gpl-3.0.html

• “Licensees” and “recipients” may be individuals or organizations.
• “The “source code” for a work means the preferred form of the work for making modifications to it.
• “Termination” — gives very specific information on days and procedure.
• non-exclusive, worldwide

Public domain

https://en.wikipedia.org/wiki/Public_domain

(no exclusive intellectual property rights apply.)

Eg.: https://github.com/metmuseum/openaccess uses https://creativecommons.org/publicdomain/zero/1.0/