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A Marketer’s Guide to Do Not Track: A Browser by Browser Breakdown

A Marketer's Guide to Do Not Track

Earlier this year, Microsoft caused a stir in the online advertising world by announcing they would be making Do Not Track the default setting on the forthcoming iteration of Internet Explorer. Even more recently, Google announced that a Do Not Track setting would be made available for their popular Chrome browser before the end of this year.

With all the conversation and the controversy surrounding Do Not Track in its various iterations, it’s worth taking a moment to gain a better understanding of what the Do Not Track standard means and has meant,  parse the difference between the various browsers’ options, and review the effects on marketers.

The History of Do Not Track

A common misconception about Do Not Track is that it is equivalent to blocking cookies. A browser can block cookies, but the Do Not Track standard that’s been dominating the news refers to something different. For a long time, the online advertising industry had tried to come up with a viable tracking opt-out that made implementation easy for consumers and adherence simple for advertisers. Prior to Do Not Track, the prevailing standard was a cookie-based system, meaning user preference was stored in a cookie. In addition to the irony of tracking those who asked not to be tracked, the solution is impermanent—as soon as someone clears their cookies (which, admittedly, does not happen with great frequency) their preference is erased.

In early 2011, Mozilla developed Do Not Track, which launched in a beta version of their Firefox browser. Users can turn DNT on by checking a box in their browser settings, and when they visit a website, a header will appear announcing that this user prefers not to be served targeted advertisements. Cookies aren’t explicitly blocked; websites and ad networks have to be trusted to respect the signal and disable targeting for those users. It was a gamble, but it paid off. Advertisers responded positively and thus a new standard was set.

Even prior to the Firefox announcement, the World Wide Web Consortium (W3C) had created a Tracking Protection Working Group, comprised of various stakeholders ranging from content sites to advertisers to consumer privacy experts (and including Mozilla among its members). In November 2011, the group announced an initial draft of an online privacy standard based largely DNT.

Breakdown by Browser


Firefox, the undisputed leader in the Do Not Track movement, has offered DNT since February 2011. Currently, 8.6% of Firefox’s web users have DNT enabled. However, based on the large percentage of users who use Firefox’s ad blocking plug-in (versus the significantly lower number of users with Chrome’s counterpart enabled), it is fair to assume that the average Firefox user is both savvier and more likely opt out of advertising than users of other browsers. Firefox’s DNT adoption rates should not be taken as a representative sample, and it can be reasonably assumed that adoption rates will be much lower for other browsers.


Back in February, Chrome announced it planned to implement a DNT standard (and Firefox reminded everyone that they’d been offering DNT for the past year). Recently, they’ve announced that a similar offering will be shipped before the end of 2012.


Safari also has currently offer a Do Not Track setting to its users, though there is no publicly available data on how many people take advantage of the offering.


Microsoft made waves this year by announcing that IE10 (which has yet to ship) will have Do Not Track enabled as a default setting. All other browsers offer DNT as an option, but one that users must enable themselves.  The widespread industry backlash largely stemmed from the fact that W3C standards require DNT to be disabled by default, requiring consumers to make an active choice about their privacy. Microsoft, prominent industry groups argued, is flouting an accepted standard and setting back the progress made by the W3C Tracking Protection Working Group and others.

Others have argued that the move is entirely competitive, and that Microsoft is not motivated by a desire to enhance consumer privacy but rather by a desire to curb their loss of market share. Still more theories have emerged—security researcher Christopher Soghoian argued, “Do Not Track by default in IE 10 isn’t an example of IE competing against Chrome, but Microsoft going for the jugular – Google’s ad revenue.” It should be noted he is hardly the only person to support this particular theory.

Rumors of Retargeting’s Demise Have Been Greatly Exaggerated 

For marketers, one question has featured prominently in the DNT debate: what will be the effects on behavioral targeting?

Typically, forms of behavioral ad targeting like retargeting significantly outperform traditional display, or even other forms of targeting like demographic or contextual targeting. Many marketers are concerned about the demise of tools they’ve grown to rely upon. If that describes your outlook, fear not, for the effects of DNT are unlikely to be particularly widespread, and are even more unlikely to deter one of the fastest growing markets in the online ad space.

Adoption rates are never likely to be particularly high, and although Internet Explorer remains the most popular browser, IE10 adoption may still be relatively anemic. Check out this breakdown from AdExchanger:

IE 9 was released to the public on March 14, 2011, but as of April 2012 had only 6.4 percent of global browser share. Even IE 8 has more. Even if, 18 months from today, IE 10 has matched IE 9?s current adoption, and nearly 100 percent of the new browser’s users stick with the default setting, that will still amount to well under 10 percent of the Internet audience telling their browsers to issue a DNT “signal.”

Additionally, there are a lot of consumers who don’t want to opt out of targeted ads. People don’t like being tracked per se, but they do like relevant advertising.

At the end of the day, Do Not Track is a good thing for both consumers and advertisers. By empowering consumers to make informed choices about privacy, we can make the web a happier and safer space. It is up to us, the online advertising industry, to better explain why targeted advertising is beneficial (who wants to see ads for things they don’t care about?), stick to ad targeting best practices, and better express our commitment to user privacy.

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