Mozilla is delaying plans to start blocking third-party tracking cookies in Firefox by default, according to an announcement. The company states that more work is needed for the anti-tracking feature. "The idea is that if you have not visited a site (including the one to which you are navigating currently) and it wants to put a cookie on your computer, the site is likely not one you have heard of or have any relationship with," explains Mozilla's Brendan Eich. "But this is only likely, not always true."