Advertisers would give just about anything to be able to lurk over your shoulder as you browse the internet. They want to know what sites you visit, how you get to them, how long you spend on them, and where you go next—along with as much personal information about you as they can get.
Of course, they don’t have to be in the room to figure any of that out. Dozens of trackers embedded in nearly every website collect information about how you interact with the page, and cookies stored in your browser tell advertisers how often you’ve visited the site before. But the holy grail is the ability to string all this information together to create profiles that corresponds to each individual user—that is, creating a complete picture of each person on the internet, beyond just scattered data points.
Companies that compile user profiles generally do so pseudonymously: They may know a lot of demographic details about you, but they don’t usually connect your behavior to your individual identity. But a group of researchers at Stanford and Princeton developed a system that can connect your profile to your name and identity, just by examining your browsing history.
When the team tested the technique on 400 real people who submitted their browsing history, they were able to correctly pick out the volunteers’ Twitter profiles nearly three-quarters of the time.