Will Scully-Power: Managing Director, Datarati

Marketers are spying on Internet users — observing and remembering people’s clicks, and building and selling detailed dossiers of their activities and interests.

The Wall Street Journal’s What They Know series documents the new, cutting-edge uses of this Internet-tracking technology.

The Journal analysed the tracking files installed on people’s computers by the 50 most popular U.S. websites, plus WSJ.com.

The Journal also built an “exposure index” — to determine the degree to which each site exposes visitors to monitoring — by studying the tracking technologies they install and the privacy policies that guide their use.

Full Story: http://blogs.wsj.com/wtk/