Privacy Badger -- an add-on for Chrome and Firefox -- says it “blocks spying ads and invisible trackers.” The EFF says that the tool, still in alpha testing, is its “answer to intrusive and objectionable practices in the online advertising industry, and many advertisers' outright refusal to meaningfully honor Do Not Track requests.”
The EFF says Privacy Badger will detect whether an ad network tracks users without their permission. If so, the tool will block ads and content from that company. The digital rights group also says that ad networks can “unblock themselves” by promising to respect do-not-track requests that users transmit via their browsers.
Every major browser developer now offers users the opportunity to send do-not-track requests to the sites they visit. But those requests don't actually block tracking. Instead, publishers and ad networks are free to respond however they want to the signals.
With a few notable exceptions -- including Twitter and Pinterest -- online publishers and ad networks largely ignore those signals. Yahoo used to be among the rare Web companies that honored the signal, but just this week changed course.
One reason why so many companies disregard the signals is that the standards group World Wide Web Consortium hasn't been able to agree on how to interpret them. Privacy advocates in the group tend to argue that users who activate a do-not-track header don't want any data about themselves to be collected by ad networks. But ad industry representatives say that they'd like to continue gathering data for analytics and market research even if the signal is turned on. (Even though ad companies often ignore do-not-track signals, the industry still allows people to opt out of receiving targeted ads. Consumers can do so by clicking on opt-out links at individual sites, or at sites run by the Digital Advertising Alliance or Networking Advertising Initiative.)
Another point of contention between the privacy advocates and industry representatives centers on Microsoft's Internet Explorer 10 browser, which automatically turns on do--not-track headers. Advocates often say that Web companies should respect all do-not-track headers, regardless of which browser people are using. But some ad industry executives have said that do-not-track requests from Internet Explorer 10 users don't reflect a decision by users.
Last week, the W3C made some progress by coming up with a tentative definition of “do not track.” The group now says that “do not track” means that users don't want data about themselves collected by ad networks. But the organization also says that ad networks should be able to collect some type of information -- such as data used for ad frequency capping -- even when people activate do-not-track. The W3C is still debating exactly what type of data can still be collected in that situation.