In 1970, MIT Ford Professor of Engineering Robert Fano wrote an essay for this magazine called "Computers in Human Society--For Good or Ill?" Having experimented with the scarce and expensive machines for more than a decade, he knew that a revolution was at hand. And he worried that if computing power did not become broadly accessible, human liberty would be gravely threatened.

Seven years before, Fano had organized Project MAC at MIT to demonstrate the feasi­bility of ­"general-­purpose, independent, on-line use of computers by a large number of people." He believed that the computer's potential lay not in its computational power but in its ability to foster "intellectual communication" and collaboration. (His insight proved true not just for intellectual communication for but every other kind, too. Throughout this issue of the magazine, we explore the rise of social networking.) With funding from the U.S. Defense Department's Advanced Research Projects Agency, whose Information Processing Techniques Office was headed by the visionary J. C. R. Licklider, Project MAC researchers perfected a time-sharing computer system that multiple users could log in to simultaneously.