[pwdisswordfish9]

Not true. It is an option by virtue of the fact that is a public repository. (If you fail to specify a license on a public repository, the terms that apply are not the default "all rights reserved [by the owner/creator]" that prohibits anyone else from using/displaying/performing or making their own copies. Instead, the terms that apply are the default terms that are specified in the GitHub TOS that you agree to--terms that, in fact, do allow forking.)

[peterdn]

I don't think it's that simple. GitHub themselves say [1]:

> You're under no obligation to choose a license. However, without a license, the default copyright laws apply, meaning that you retain all rights to your source code and no one may reproduce, distribute, or create derivative works from your work.

Yes, it does note immediately below that "if you publish your source code in a public repository on GitHub, according to the Terms of Service, other users of GitHub.com have the right to view and fork your repository". But that doesn't mean it's open source. You probably can't/shouldn't create derivative works with your forks. And you definitely wouldn't be allowed to just use this code in a commercial product, for example.

[1]: https://docs.github.com/en/repositories/managing-your-reposi...

[pwdisswordfish9]

> GitHub themselves say [1]

Irrelevant. You're quoting docs.github.com, which is neither authoritative (docs are written to GitHub's documentation standards, not by their legal team), nor is it always up-to-date or well informed for the non-legal matters where it ventures to comment about the state of GitHub's products/services.

> that doesn't mean it's open source

Strawman. The question is "can you fork/copy?", not "is it open source?". The answer to the former is "absolutely yes, unequivocally". Anyone saying otherwise is wrong.