The practical result of the change is that the DoubleClick ads that follow people around on the web may now be customized to them based on the keywords they used in their Gmail. It also means that Google could now, if it wished to, build a complete portrait of a user by name, based on everything they write in email, every website they visit and the searches they conduct.
The move is a sea change for Google and a further blow to the online ad industry’s longstanding contention that web tracking is mostly anonymous. In recent years, Facebook, offline data brokers and others have increasingly sought to combine their troves of web tracking data with people’s real names. But until this summer, Google held the line.
To opt-out of Google’s identified tracking, visit the Activity controls on Google’s My Account page, and uncheck the box next to “Include Chrome browsing history and activity from websites and apps that use Google services.” You can also delete past activity from your account.
“The fact that DoubleClick data wasn’t being regularly connected to personally identifiable information was a really significant last stand,” said Paul Ohm, faculty director of the Center on Privacy and Technology at Georgetown Law.
“It was a border wall between being watched everywhere and maintaining a tiny semblance of privacy,” he said. “That wall has just fallen.”