Why online tracking is getting creepier | Ars Technica

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The marketers that follow you around the Web are getting nosier.

Currently, many companies track where users go on the Web—often through cookies—in order to display customized ads. That's why if you look at a pair of shoes on one site, ads for those shoes may follow you around the Web.

But online marketers are increasingly seeking to track users offline as well, by collecting data about people's offline habits—such as recent purchases, where you live, how many kids you have, and what kind of car you drive.