[Lyapunov_Lover]

Yeah, I think people are mostly confused here. Open access is a thing when we're talking about peer-reviewed journals. arXiv hosts preprints, meaning they are available before the peer-review process has proceeded. So calling arXiv papers "open access" is misleading, because that label carries the assumption of peer review. And I've never heard of "gold open access" either. Researchers paying to have their papers published is standard, open access or not. That's just how it works. If someone is using the term "gold open access" I'm just going to assume they have no idea how science publishing operates.

[chaosite]

I mean, these terms are defined and widely understood, so, um, no.

"gold open access" is where you publish to a peer-reviewed open-access journal, which may or may not involve the author paying for the privilege.

"green open access" is where you publish to any peer-reviewed journal, and then the author self-archives the paper somewhere, like an institutional website, arXiv (as a "post-print", not a pre-print), or even Sci-Hub.

There are discussions involved about copyright and license and so on, but that's the gist of it.