Every Click You Make

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NebuAd promises to protect users' privacy in a couple of ways.

First, every user in the NebuAd system is identified by a number that the company assigns rather than an Internet address, which in theory could be traced to a person. The number NebuAd assigns cannot be tracked to a specific address. That way, if the company's data is stolen or leaked, no one could identify customers or the Web sites they've visited, Dykes said.

Nor does NebuAd record a user's visits to pornography or gaming sites or a user's interests in sensitive subjects -- such as bankruptcy or a medical condition such as AIDS. The company said it processes but does not look into packets of information that include e-mail or pictures.

What it does do is categorize users into dozens of targeted consumer types, such as a potential car buyer or someone interested in digital cameras.

Dykes noted that by a couple of measures, their system may protect privacy more than such well-known companies as Google. Google stores a user's Internet address along with the searches made from that address. And while Google's mail system processes e-mail and serves ads based on keywords it finds in their text, NebuAd handles e-mail packets but does not look to them for advertising leads.

Such privacy measures aside, however, consumer advocates questioned whether monitored users are properly informed about the practice.

Knology customers, for example, cull the company's 27-page customer service agreement or its terms and condition for service to find a vague reference to its tracking system.

"They're buried in agreements -- who reads them?" said David Hallerman, a senior analyst at eMarketer. "The industry is setting itself up by not being totally transparent. . . . The perception is you're being tracked and targeted."