As more and more people join social-networking sites, Danah Boyd is asking and answering some uncomfortable questions about these online communities. Among other things, she has detailed how race has been a factor in some users' migration from MySpace to Facebook, how social networks are changing the way teenagers relate to one another, and how the Internet alters the way people think about privacy.

Working as an advisor, Boyd has shaped the policies of companies like Google and LiveJournal. Now employed by Microsoft Research New England, she has been talking with government regulators and privacy advocacy groups to determine how best to help users protect their personal information. She believes that privacy regulation is inevitable and is trying to guide the industry and regulators toward a set of mutually acceptable rules.

Critical to any such solution, Boyd says, is making sure that people can control what happens to their personal data after it has been entered into a social network.--Erica Naone