[tossimba]

foobar.com never has access to cookies from google.com. when requests are sent to google.com, cookies are added. when you load google.com, JS can access the google.com cookies.

google analytics: google.com tracking cookie is to identify the user. the js in the page knows the current website and tells google "im here". the dominance of google analytics and adsense means users are tracked wherever they go (because google is always there and recording)

[thisacctforreal]

However, the browser can choose not to send any cookies to google.com when making requests to google from mycuteblog.com.

It's known as blocking third-party cookies, a setting in most browsers. It does sometimes break when auth flows use separate domains to hold auth cookies, and other valid use-cases.