Technology

They are usually separate things. Cookies are produced/saved locally, to be read in the next visit (by the same website or maany websites basically forever unless you use firefox containers or at least clear them once in a while). There's also local storage which is different but can also be used to identify you across the web. Ads, trackers, all of these categories are often made of many small components: you read a single article on a "modern" newspaper website, hundreds of connection are being made, different tiny scripts or icons or images are being downloaded (usually from different subdomains for different purposes but there's no hard rule). It's possible to block one thing and not another. For example I can block Google Analytics (googletagmanager) which is a tracker, but accept all of Google's cookies.

The way I'm reading it, they allow the third party cookies to be used within the actual site you're on for analytics, but prevent them from being accessed by that third party on other sites.

But I just looked at the linked article's explanation, and not a technical deep dive.

So that's what third party cookies are. What this does is make it so that when you go to example.com and you get a Google cookie, that cookie is only associated with example.com, and your random.org Google cookie will be specific to that site.

A site will be able to use Google to track how you use their site, which is a fine and valid thing, but they or Google don't get to see how you use a different site. (Google doesn't actually share specifics, but they can see stuff like "behavior on one site led to sale on the other")

We'll have to see what happens but what you are talking about is what Mozilla calls Third-Party Cookies and... they are aware of it.

https://support.mozilla.org/en-US/kb/third-party-cookies-firefox-tracking-protection#:~:text=Third%2Dparty%20cookies%20are%20cookies,considered%20a%20third%2Dparty%20cookie.

I can't entirely tell if that means they will be put in the facebook cookie jar or if it will be put in the TentaclePorn Dot Org (don't go there, it is probably a real site and probably horrifying) cookie jar. If the former? Then only facebook themselves have that which... is still a lot better I guess? If the latter then that is basically exactly what we all want but a lot of sites are gonna break (par for the course with Firefox but...).