For the website you are online with, you need to accept their cookies. Cookies contain information the website stores about you, your system, what you do on the site . . . . . If these cookies are blocked, the website may not work properly.

On the other hand, there are also 3rd party cookies. These are for websites that you are currently Not online with. Such does not mean there is a security breach. You would have to contact the website support and ask them about this.

https://support.mozilla.org/en-US/kb/websites-say-cookies-are-blocked-unblock-them

Those cookies are possibly session cookies that expire when you close Firefox.

• https://developer.mozilla.org/en-US/docs/Tools/Storage_Inspector

Thanks, but you provided general information on how cookies work. Knowing absolutely everything about cookies wouldn't answer my question. I'm asking about what Firefox does in a specific situation.

A website says I need to allow their cookies to do some nebulous thing. If I say "Okay", Firefox is still in ultimate control of how the cookies are handled. Does Firefox treat it as "Okay, you can do that, as long as it's in line with my cookies preferences in Firefox settings"? Or does Firefox treat it as "Okay, you can do that, and either my cookies preferences in FireFox settings will be changed accordingly, or you'll be added to an Exceptions list"? Or does Firefox treat it as "Okay, you can do that, even though it goes against my cookies preferences in Firefox settings"?

A website cannot override your Firefox settings, no. Firefox isn't even paying attention to whether there is a cookie consent in the page -- for all it knows, that button ordered a coffee. When the server or a script in the page wants to set a cookie, Firefox's response is based on whether that is allowed by your settings.

Thank you, this is very helpful. I'm glad that this is what Firefox does.