Ethan Zuckerman is sorry. Zuckerman, who leads the Center for Civic Media at MIT, says he didn't realize what he was bringing into the world when he wrote the code for the first pop-up ad more than 20 years ago. He tells the story of how it happened in an exquisite essay about how the ad-based business model came to dominate the Internet—and why it really shouldn't (and what we ought to do about it). It was the mid-1990s, and Zuckerman was working as a designer and programmer for Tripod.com: "At the end of the day, the business model that got us funded was advertising. The model that got us acquired was analyzing users’ personal homepages so we could better target ads to them. Along the way, we ended up creating one of the most hated tools in the advertiser’s toolkit: the pop-up ad."