Microsoft recently announced that Internet Explorer 9, will support the standard, which sends a message to Web sites that you would like to opt out of tracking. Combine that with Do Not Track support in Firefox 4 and Chrome and it seems like opting-out is the new hot browser feature of the year. But how does Do Not Track work and what value does it bring to users?

While several solutions to the online tracking problem have been proposed (such as users blocking tracking code or using cookies to opt-out), Do Not Track is a relatively simple solution that adds an html header to every piece of information you send out to Web sites indicating that you don't want to be tracked. This header can this be read by sites that will, in theory, then opt you out of their tracking.

At the moment, however, that header doesn't have any effect on tracking. The standard depends on each tracking site honoring the do not track header and so far no tracking service complies with the standard - or has even said it plans to. For now Do Not Track is more the promise of a solution than an actual escape from online tracking.

A second problem is a lack of nuance in the standard itself. Chrome and Firefox treat Do Not Track as a simple binary, you either allow tracking or you don't. While this is probably good for most users, I have to wonder: Don't we WANT to be tracked sometimes? I can't say I'd cry myself to sleep if random Web sites stopped showing me targeted ads, but when Amazon suggests products to me, based on tracking my recent purchases and the pages I've viewed on the site, those recommendations are actually fairly useful. Sometimes the fact that the Internet knows a freakishly large amount about me is actually helpful.

Of course, this binary state of affairs isn't likely to last forever. In fact, IE9 will give you more control over Do Not Track technology by allowing for exceptions for certain sites, such as Amazon, that you might feel produce something you value by tracking you.