By Kevin Purdy

What "Do Not Track" Is and Why It's Important

What "Do Not Track" Is and Why It's Important What's so bad about ad tracking on the web, a.k.a. behavioral targeting? Nothing, if you don't mind being a living stereotype. No, seriously—that's what much of the fuss over "Do Not Track" browser options and opt-out options is about. Ad companies watch what you do online, and they make bold assumptions about you. How you feel about that is up to you.

What is Tracking (a.k.a. Behavioral Targeting)?

You might go months and months without ever noticing it, but surf around online and look closely at the edges of your web pages once in a while. Unless you've tweaked the settings on your browser, you're allowing not just the sites you visit, but the ads they display, to learn a bit more about you.

What "Do Not Track" Is and Why It's Important How does it work in practice? Let's take Google's ad network as an example. Yesterday, I searched Google because I couldn't remember how many tablespoons of coffee to put into my use-your-own-coffee Keurig K-Cup.

What "Do Not Track" Is and Why It's Important Later that day, doing research for this post, I noticed a peculiarly specific ad in an odd context. Do most Wired readers need Keurig refills? Maybe, but, wow, what a coincidence!

What "Do Not Track" Is and Why It's Important During an afternoon lull, I did some daydreaming about, well, the hardware specs on the ultra-light ThinkPad 410s versus a MacBook Air. Hey, it's my own version of a fantasy league.

What "Do Not Track" Is and Why It's Important Later on, when I'm really, really off the beaten path, I'm looking for a specific clip from a RoboCop film when, lo and behold, there's special pricing on the ThinkPad line, right beneath the guy who ended RoboCop's humanity!

This is the most obvious level of cookie-based browser tracking: you searched for terms on Google, and Google, which also runs advertising on its Reader and YouTube services, gently nudged you toward those same terms, or related things, on ads you saw later on. A sub-level of that tracking, one that's generally more innocuous, occurs within web sites that use web analytics—which is to say, all of them. Sites track you as you arrive from specific links or searches, move through their pages, click on things, request images, and the site owners and content editors can learn from how traffic flows through their pages, as people stop on certain pages for certain lengths, and so on.

How Do Sites and Advertisers Track Me?

On the most basic level, it's very simple: your browser accepts a cookie from a site, generally as a means of storing your login status, site preferences, or the like. If your browser also accepts third-party cookies, those are used to customize the ads you see, and log some of your activity.

As we've previously set out in the truth about browser cookies, these third-party cookies—not from the site you visit, but from an ad supplier they partner with—don't actually know anything about you, the user, in terms of your identity, where you live (to the street address level, at least), or other unique identifiers. What they do know is about you, generally, as a web user. Within their wide-reaching networks, sellers of advertising can build up a profile of your habits, and use their best guesses to figure out what you might be interested in buying.

AOL, in seeking to explain ad tracking in a fairly simple, innocuous way, conceived of a penguin-guided illustration (or perhaps video) that may have never seen the light of day. But the leaked shot list and sketches do provide a nicely simple explanation.

Why Should I Care if Some Computer Knows What I'm Looking For?

All that seems fairly straightforward: you searched for ThinkPads, so maybe you'd be interested in seeing ThinkPad deals. Over a long enough timeline, though, lots of those searches, clicks, and ad impressions add up to build a profile. You search for ThinkPads, you're into DIY Keurigs, you search out RoboCop clips on YouTube. If an advertising network wants to convince a video game maker, or maybe an Android phone retailer, that their ads are hitting the right marks, all that pseudo-confidential data makes one (okay, me) a pretty likely target.

Finally, there's the deep, deep well of information social-oriented sites and apps like Facebook have about not only what you search for and click online, but what you "Like," which of your friends you interact with most, your common interests, your professions, coupon deals you've clicked on, and much, much more. Facebook and sites like it sit right between relatively innocuous on-site analytics and behavior-trailing networks. More on that in a bit.

The more alarming aspect of what's sometimes referred to as behavioral targeting isn't a certain kind of tracking, or any particular browser aspect, but simply the unanswered questions about the data that's being grabbed by ad firms:

How long should networks hold onto your unique ID, set in your cookie, as you browse the web?
How much data should they be able to glean from you?
Are there certain kinds of searches and page visits that shouldn't be tracked or monitored?
What rights do ad networks have to sell or store your data?

Who Are the Firms Tracking Me?

What "Do Not Track" Is and Why It's Important Short answer: every web-based advertising network that wants to make money.

Better answer: Check out the firm-by-firm specifics for yourself:

What "Do Not Track" Is and Why It's Important The online ad industry has made efforts to make itself more transparent. Most of the major networks go out of their way to explain their data retention and behavioral policies, if you've got the time and inclination to look around. And at sites like the Network Advertising Initiative and this multi-organizational opt-out site, you can selectively click to opt out of being tracked by AOL, Google, Fox, or most of the other ad networks.

But the next time you wipe out your browser cache, or run some other kind of cleaning operation, you're back in the ad-tracking game.

Where and How Can I Get Away from Ad Tracking?

Every browser these days offers a private/"Incognito" mode, and that's the safest way to play it, at least for short stretches of browsing you want to keep (generally) un-linked to your other habits. But for the general browsing populace, that's not a real option. This is where Firefox 4, Internet Explorer 9, a Chrome extension, and a bit of potential (U.S.) legislation come into play.

What "Do Not Track" Is and Why It's Important In the nightly builds of Firefox 4, an option is provided in your Privacy settings to "Tell web sites I do not want to be tracked." A similar function has appeared in Internet Explorer 9's release candidate. There's nothing built into Chrome, though that browser moves quickly; in the meantime, a very handy extension from Google itself allows you to make your opt-out ad-tracking choices stick, whether or not you've wiped your cache. (Image via WebMonkey).

All these options are, however, voluntary on the part of the advertising networks, or at least very tiresome to manage for the individual. On a broad level, major industry players may adhere to principles, but the Federal Trade Commission has suggested that firmer, more universal rules are needed to govern data collection on the web. One such bill, from Rep. Jackie Speier (D-California), looks like a promising initiative, but as Wired points out, it's hard to write a bill that covers behavior by the analytics firm almost every site uses, the sticky-but-generally-anonymous ad tracking of networks, and the deep data mine that Facebook possesses but rarely moves on, and, generally, only inside its own network. And none of the rules in Speier's bill would apply to ad firms that haven't stepped forward to make note of their privacy policies.

As the How-To Geek pointed out, ad tracking isn't, in itself, necessarily a bad thing. The alternative is dumb ads aimed at the widest possible audience—think of "(Your City) Woman Earns $78/Hour Working From Home!" But for now, most of us are stuck between a rock and a hard place: regularly monitoring our cookies, opt-outs, and other micro-data, or living a casual life online and hoping that firms are only loosely associating the things we do, and forgetting about them in relatively short order.

Where do you draw the line on online ad tracking? What tech resources have you turned to when you want a bit more privacy? Tell us your take on ad tracking, behavioral targeting, and the cookie cluster in the comments.