Marketers’ demand for detailed information about individuals is at an all-time high. In the past three years, the personal-data business has exploded, with hundreds of companies tracking online behavior.
As a result, basic information about Internet users—gender, age, location, income and interests—is now a commodity, ad executives say. So, to gain a competitive edge, companies are assembling more detailed profiles about people that can include thousands of data points ranging from political interests to marital status. Recently, one online-dating service was found sending information about its users’ “drug use frequency” to an online-tracking company.