The feature, which is set to arrive in the first release candidate of IE9 early next year, uses a list to tell the browser which third-party page elements sites can and cannot be blocked from tracking. This includes elements ranging from advertisements to more mundane things like embedded widgets from particular providers.
On Microsoft’s IE blog, Dean Hachamovitch, head of Internet Explorer development, explained how it works:
A Tracking Protection List (TPL) contains Web addresses (like msdn.com) that the browser will visit (or “call”) only if the consumer visits them directly by clicking on a link or typing their address. By limiting the calls to these Web sites and resources from other Web pages, the TPL limits the information these other sites can collect.
You can look at this as a translation of the “Do Not Call” list from the telephone to the browser and web. It complements many of the other approaches being discussed for browser controls of Do Not Track.
In a Webcast announcing the feature, Hachamovitch said most users have “little awareness of who can track their activity,” and that the feature stemmed from that. Hachamovitch also attributed the creation of the feature to the company’s more open approach to developing features for IE9.