Update (27th Oct 2012): I told you so! Yahoo will ignore DNT from IE10 for exactly the reason I cite below.
Microsoft just announced that the “do not track” opt-out would be on by default in Internet Explorer 10. This is a boneheaded move.
“Do not track” is a standard through which a web browser can inform a web page that the user does not wish to be tracked by third-party websites for the purpose of advertising. So far as I can tell, respecting this is entirely voluntary on the part of the advertisers.
Advertisers often use browser cookies to track users, this allows them to target advertising specifically to people who’ve visited their website, for example. Google and Microsoft both do it, it’s fairly standard practice these days. Typically the advertiser isn’t tracking you as an individual, all they know is that you may have previously visited a particular website.
To explain why Microsoft’s move is boneheaded, I’ll relate a story from the early days of Revver, the online video sharing website that I co-founded back in 2004.
We had decided to let video uploaders tell us whether the video contained any content that is not appropriate for children as part of the upload process. The vast majority of our users did exactly this and all was well, until at some point we realized that people were uploading some pretty serious pornography that we weren’t comfortable with even if it was marked as “adult” by the uploader.
Our panicked solution was to simply remove all videos marked as “adult” from the site, and prevent any further uploads where the videos were so-marked.
Of course you can predict the result: people immediately stopped marking videos as “adult”, making our task vastly more difficult.
The moral? Don’t expect people to do something voluntarily if you are then going to use it against them.
I think Microsoft has just made exactly the same mistake. Previously I think there was a reasonable chance that advertisers would choose to respect this, since only a minority of users are likely to enable it, and those are the people that really care about not being tracked.
But if it is enabled by default in Internet Explorer 10, advertisers now have no idea whether the user really cares about being tracked, and as a result they are far less likely to respect it.
Looking at it a different way, Microsoft just gave advertisers the perfect excuse to ignore DNT, because they can correctly claim that in most instances the user will have made no conscious decision to enable it.