The privacy issues raised by this research are of a technical nature and invite technical solutions. These solutions often come in the form of add-on software users may install in their Web browsers. Such browser add-ons have proven effective at blocking certain types of behavioral tracking.19,25 However, this type of solution places a burden on users and has not been broadly effective. As measurement research has shown, tracking has only increased over the past decade despite technical efforts to rein it in.