What is Copyleft? - GNU Project

The Free Software Foundation classifies licenses as free software, copyleft and compatible with the GNU GPL (or not). FSF was prompt to recognise the EUPL as a “Free software license” and “copyleft”.

as nerdy as needed.

My name is Lukas Rotermund, and I am a backend software developer working entirely remotely on PHP Symfony APIs and e-commerce services for the tasko Products GmbH, a leading, European brand for leather goods and luggage. I strongly believe in copyleft licences and free software. I support the vast majority of the free software projects I use by making monthly donations to their foundations or to the maintainers directly.

A comparison of PlaneShift’s claims of software freedom benefits with their nonfree artwork license.

Requiring the inclusion of free license text is unnecessary and harmful in some kinds of works. Alternatives are presented.