Howard Rheingold

As early as 1985 Rheingold wrote Tools for Thought, about the people who imagined the computer as an instrument for thinking rather than calculating. But it was The Virtual Community, in 1993, that made him the person journalists called when they wanted the net explained. The book drew on his own time on The WELL: neighbours who had never met, yet raised money, kept vigil at sickbeds and bickered like relatives.

He saw the downside early, and the book itself spends real space on surveillance and commercialisation. Later came Smart Mobs (2002), on the mobile phone as a coordination tool. He was an optimist at a time when that was easy, but with more caveats than he usually gets credit for.