> But I'm very thankful that the original author just posted his code to Github to make this possible.
That does not make forking possible. There are many projects on GitHub that are not open source. One should be thankful for the author for licensing their software using an open source license.
I think you can still fork it if it's not free software, but it needs to be a private fork. I think that, unless they say they are distributing their software on certain conditions, just copyright alone wouldn't prevent you from modifying the code for personal usage.
> just copyright alone wouldn't prevent you from modifying the code for personal usage.
This is correct. Copyright prevents you from distributing the protected work. It doesn't prevent you from taking it and doing whatever else you want with it.
(I'm ignoring the DMCA anti-circumvention clause here because that's a whole different issue and rarely actually comes into play)
> But I'm very thankful that the original author just posted his code to Github to make this possible.
That does not make forking possible. There are many projects on GitHub that are not open source. One should be thankful for the author for licensing their software using an open source license.