Even if you're generally familiar with the idea of data collection for targeted advertising, the number and variety of these data collectors will probably astonish you. Allow me to introduce the list of companies that tracked my movements on the Internet in one recent 36-hour period of standard web surfing: Acerno. Adara Media. Adblade. Adbrite. ADC Onion. Adchemy. ADiFY. AdMeld. Adtech. Aggregate Knowledge. AlmondNet. Aperture. AppNexus. Atlas. Audience Science.

And that's just the As. My complete list includes 105 companies, and there are dozens more than that in existence. You, too, could compile your own list using Mozilla's tool, Collusion, which records the companies that are capturing data about you, or more precisely, your digital self.

While the big names -- Google, Microsoft, Facebook, Yahoo, etc. -- show up in this catalog, the bulk of it is composed of smaller data and advertising businesses that form a shadow web of companies that want to help show you advertising that you're more likely to click on and products that you're more likely to purchase.

To be clear, these companies gather data without attaching it to your name; they use that data to show you ads you're statistically more likely to click. That's the game, and there is substantial money in it.

As users, we move through our Internet experiences unaware of the churning subterranean machines powering our web pages with their cookies and pixels trackers, their tracking code and databases. We shop for wedding caterers and suddenly see ring ads appear on random web pages we're visiting. We sometimes think the ads following us around the Internet are "creepy." We sometimes feel watched. Does it matter? We don't really know what to think.



The issues the industry raises did not exist when Ronald Reagan was president and were only in nascent form when the Twin Towers fell. These are phenomena of our time and while there are many antecedent forms of advertising, never before in the history of human existence has so much data been gathered about so many people for the sole purpose of selling them ads.

"The best minds of my generation are thinking about how to make people click ads," my old friend and early Facebook employee Jeff Hammerbacher once said. "That sucks," he added. But increasingly I think these issues -- how we move "freely" online, or more properly, how we pay one way or another -- are actually the leading edge of a much bigger discussion about the relationship between our digital and physical selves. I don't mean theoretically or psychologically. I mean that the norms established to improve how often people click ads may end up determining who you are when viewed by a bank or a romantic partner or a retailer who sells shoes.

Already, the web sites you visit reshape themselves before you like a carnivorous school of fish, and this is only the beginning. Right now, a huge chunk of what you've ever looked at on the Internet is sitting in databases all across the world. The line separating all that it might say about you, good or bad, is as thin as the letters of your name. If and when that wall breaks down, the numbers may overwhelm the name. The unconsciously created profile may mean more than the examined self I've sought to build.