Microsoft has revealed a new feature that will ship with Internet Explorer 9 to help users avoid the online tracking that is now widespread on the Web and is used to power behavioral advertising. The new Tracking Protection Lists will tell the browser which third-party content to permit and which to prohibit. Tracking Protection Lists will be an opt-in feature, and Microsoft says that it will not provide any lists itself. Instead, third parties can provide lists to end-users. As such, the lists may come from privacy advocacy groups, ad-blocking advocates, or individuals who want to block certain content.