Also, why is it that different things enter the public domain at different times? For example, I learned of a movie from like the 1970s called The Last Man on Earth that is public domain, or at least I’m guessing it’s public domain, and yet it’s from the 1970s, where this is talking about stuff from 1929. I obviously know some stuff is made and released immediately into the public domain, such as open source software, etc. But I wouldn’t figure a movie would be like that.
Just FYI, most open source software is not in public domain, it is protected by the same copyright we are talking about here, except the author made it available under certain conditions (the licence).
The MIT is, but GPL is actually very restrictive. For example, it disallows publishing derivative works without those being licensed under the same terms (or newer GPL versions). That’s why commercial companies are reluctant to use GPL-licensed code in their products.
This has to do with how copyright laws changed over time, for example there used to be a requirement in the US for works to have a copyright notice, or for copyright to be renewed, so some things that didn’t meet those requirements became public domain earlier than they could have if the copyright holder had cared about all the formalities.
Also, why is it that different things enter the public domain at different times? For example, I learned of a movie from like the 1970s called The Last Man on Earth that is public domain, or at least I’m guessing it’s public domain, and yet it’s from the 1970s, where this is talking about stuff from 1929. I obviously know some stuff is made and released immediately into the public domain, such as open source software, etc. But I wouldn’t figure a movie would be like that.
Just FYI, most open source software is not in public domain, it is protected by the same copyright we are talking about here, except the author made it available under certain conditions (the licence).
Good point, I didn’t even think of that because the GPL and MIT are so permissive.
The MIT is, but GPL is actually very restrictive. For example, it disallows publishing derivative works without those being licensed under the same terms (or newer GPL versions). That’s why commercial companies are reluctant to use GPL-licensed code in their products.
This has to do with how copyright laws changed over time, for example there used to be a requirement in the US for works to have a copyright notice, or for copyright to be renewed, so some things that didn’t meet those requirements became public domain earlier than they could have if the copyright holder had cared about all the formalities.