The 2010 TIME 100

Jaron Lanier, 49, is many things — composer, performer, computer scientist, philosopher — but one thing he is not is a machine. His book You Are Not a Gadget, published this year, compels readers to take a fresh look at the power — and limitations — of human interaction in a socially networked world.

In the 1980s, Lanier's pioneering work on virtual reality reshaped our concept of how sensory interfaces enable human-computer interaction. As a musician, he has fused Eastern and Western traditions with artistry and technology. His ability to synthesize these forces — so often held in opposition — is the hallmark of his mind and the guiding philosophy of his book, in which he celebrates the potential of the Internet but also laments the way its misuse can suppress the individual voice.

With an expertise earned through decades of work in the field, Lanier challenges us to express our essential humanity via 21st century technology instead of disappearing in it.

Reed is Microsoft's vice president for extreme computing

TIME 100 Social-Networking Index: 0