Should Personal Data Be Personal?

Personal data is the oil that greases the Internet. Each one of us sits on our own vast reserves. The data that we share every day — names, addresses, pictures, even our precise locations as measured by the geo-location sensor embedded in Internet-enabled smartphones — helps companies target advertising based not only on demographics but also on the personal opinions and desires we post online. Those advertising revenues, in turn, make hundreds of millions of dollars for companies like Facebook, which announced last week that it was going public in what is expected to be the largest I.P.O. in digital history. And those revenues help to keep the Web free of charge.

But there is a price: that data about our lives and wants are collected, scrutinized and retained, often for a long time, by a great many technology companies. Personal data is valuable. In the United States alone, companies spend up to $2 billion a year to collect that information, according to a recent report from Forrester Research.