Firefox Rolls Out Total Cookie Protection By Default To All Users | The Mozilla Blog
Starting today, Firefox is rolling out Total Cookie Protection by default to all Firefox users worldwide, making Firefox the most private and secure major browser available across Windows, Mac and Linux. Total Cookie Protection is Firefox's strongest privacy protection to date, confining cookies to the site where they were created, thus preventing tracking companies from using these cookies to track your browsing from site to site.
https://blog.mozilla.org/en/products/firefox/firefox-rolls-out-total-cookie-protection-by-default-to-all-users-worldwide/