They know what you’re shopping for

Companies today are increasingly tying people’s real-life identities to their online browsing habits. Research conducted by the Wall Street Journal on the practices of more than a thousand websites shows that the border between our public and private lives is blurring still more.

“The use of real identities across the Web is going mainstream at a rapid clip. A Wall Street Journal examination of nearly 1,000 top websites found that 75% now include code from social networks, such as Facebook’s FB +0.50% “Like” or Twitter’s “Tweet” buttons. Such code can match people’s identities with their Web-browsing activities on an unprecedented scale and can even track a user’s arrival on a page if the button is never clicked.

In separate research, the Journal examined what happens when people logged in to roughly 70 popular websites that request a login and found that more than a quarter of the time, the sites passed along a user’s real name, email address or other personal details, such as username, to third-party companies. One major dating site passed along a person’s self-reported sexual orientation and drug-use habits to advertising companies.

As recently as late 2010, when the Journal wrote about Rapleaf Inc., a trailblazing company that had devised a way to track people online by email address, the practice was almost unheard-of. Today, companies like Dataium are taking the techniques to a new level.

Tracking a car-shopper online gives dealers an edge because not only can they tell if the person is serious—is he really shopping for red convertibles or just fantasizing?—but they can also gain a detailed understanding of the specific vehicles and options the person likes.”

(Make sure to explore the video and the interactive graphics.)