"Do Not Track" capabilities have been controversial ever since they first appeared in Firefox 4 back in 2011, but earlier this year the battle became even more intense when Mozilla announced that it planned to begin blocking third-party cookies by default.
Two groups representing the online ad industry spoke out in bitter protest, charging that the move is "really little more than one company imposing its will in order to control its consumers' online experience," as the Association of National Advertisers (ANA) put it.
Mozilla appears undaunted, however, and on Friday its free and open source Firefox 22 browser appeared in the early, pre-beta Aurora channel as planned, complete with the auto-block privacy features that were so hotly protested.
So far, Do Not Track capabilities have taken the form of a header in Firefox giving users a way to opt out of having their browsing movements tracked by advertisers.
Since it was first implemented, this choice has been represented as a checkbox in the "Privacy" tab within Firefox Preferences that users could select to indicate that they do not want to be tracked.
With Firefox 21, which reached the Beta channel last Thursday, Mozilla tweaked that implementation to give users three options: "Do Track," "Do Not Track," and "no preference," as shown above.
Blocked by default
With Firefox 22, however, which is now in the early Aurora channel, cookies are blocked by default unless they're from a site the user has already visited.
"Users of this build of Firefox must directly interact with a site or company for a cookie to be installed on their machine," wrote Alex Fowler, Mozilla's global privacy and public policy leader, in a blog post earlier this year.
Though it will be enabled by default, users will have a way to disable the automatic blocking via the "History" subsection under "Privacy," as shown below.