Age: 47
Occupation: Internet guru, author
Previous TIME 100 appearances: 0
From speaking at TED conferences to writing a cover story for Foreign Affairs, Clay Shirky is everywhere, not unlike the technologies he's made a career out of studying and extolling. The NYU faculty member is the author of 2008's Here Comes Everybody — subtitled The Power of Organizing Without Organizations, which pretty much captures the powerful idea at the center of the book. In 2010, he again drove conversation about the potential of social media with Cognitive Surplus: Creativity and Generosity in a Connected Age. Particularly in a year of multiple people-powered revolutions, his voice on the relationship between the Internet and society is a significant one.