Facebook won’t stop selling ads anytime soon. But the ad business has changed in the last few decades, and data is at the heart of its new strategy. All this week on Marketplace Tech, we’re focusing on the data economy and how we got here. Host Molly Wood speaks with Safiya Noble, a professor at the University of Southern California's Annenberg School for Communication, about the evolution of advertising technology and how much it now relies on personal information, such as what Disney princess each of us is.