Yes of course, that's how cookies work. And disabling third-party cookies will stop the browser from receiving and sending to any third parties. In your browse

Yes of course, that's how cookies work. And disabling third-party cookies will stop the browser from receiving and sending to any third parties. In your browser, you have several options to deal with cookies: allow all of them, allow none, or disable third-party cookies only. Let's say I visit attacker-site.com, which includes both local content and stuff from other domains: attacker-site.com |`-- tracking-script.js |`-- tracking-image.gif |`-- facebook.com/me `--- twitter.com/tweet-button.png Content from other domains is third-party content by definition, and leads to third-party requests, in this case to facebook.com and twitter.com. If third-party cookies are disabled, those requests will will not include any cookies. Even if I'm logged in to Facebook, to attacker-site.com it will appear as if I'm not.