November 03, 2011, 5:36 PM — Think Web trackers aren't following you? Think again. Just by visiting this Web site, roughly half a dozen ad networks and Web analytics companies have deposited tracking cookies on your machine. Don't freak out, it's not as bad as it seems. In fact, there's an awful lot of hype, fear, and misinformation surrounding Web tracking -- and both sides are guilty of overstating the dangers of tracking, as well as the benefits.
How much do you know about Web tracking? Take the following True/False quiz to find out. What follows is semi-informed opinion mixed with facts -- which is the way we like to roll here at TY4NS.
True or False: Only a handful of companies track users across the Web.
Actually, more than 800 companies drop tracking cookies on people's computers, according to Evidon, which helps advertisers comply with self regulatory programs. Ever hear of Adfonic, Clicksor, or VigLink? Probably not. But they may have heard of you.
True or False: Trackers know everything about you and your Web surfing history.
First, tracking cookies don't actually track people, they track browsers. So while it's possible a Web tracker will know everything your browser did -- or pretty close to it -- it won't necessarily know whose fingers were on the keyboard at any time, or what you did using another browser or a different machine.
Second, most trackers only know that you're you -- or that your browser is your browser -- via a unique identification number placed inside a cookie, not by your name. (Though not always; see the next question.)
Third, tracking cookies only record your Web surfing habits on sites that use the same ad networks. For example, Doubleclick knows the sites you've visited that also display Doubleclick ads, but it won't know what sites you visited that use only 24/7 Real Media ads, and vice versa. Of course, these days nearly every ad-supported site uses tracking cookies from multiple networks, so the odds are good both Doubleclick and 24/7 Real Media know where you've been.
Finally, the information they do collect is extremely crude. While Web advertising networks collect the URLs of the sites you've visited, the ads you've seen, and what you've clicked on, they parse this information into generic "audience segments" -- like your age, gender, and interests -- which they use to deliver more relevant ads to you. (And which are often laughably inaccurate.) Evidon's Web site offers a simple tutorial explaining how this works.