GNU General Public License (GPL)

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

• “A license for software and other kinds of works.”
• “Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.”
• “The Program” refers to any copyrightable work licensed under this License. Each licensee is addressed as “you”. “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. “Object code” means any non-source form of a work."
• “This License explicitly affirms your unlimited permission to run the unmodified Program.”
• “Conveying Non-Source Forms” = hardware.
• “Termination” — gives very specific information on days and procedure.
• An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party’s predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.
• Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor’s essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.
• A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. — (License vs Patent: A patent is a legal right to exclude others from doing (making, using, selling) etc. what the patent covers. The legal right is owned by the patent owner (with some exceptions). On the other hand, a license is a legal right to not be excluded from doing what the patent covers. The license is granted by the patent owner to the licensee (with some exceptions), usually in exchange for something that benefits the patent owner.)

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/