If I had told you 25 years ago that, in a quarter century's time, one-third of the human race would be communicating with one another in huge global networks of hundreds of millions of people -- exchanging audio, video, and text -- and that the combined knowledge of the world would be accessible from a cellphone, that any single individual could post a new idea, introduce a product, or pass a thought to a billion people simultaneously, and that the cost of doing so would be nearly free, you would have shaken your head in disbelief. All are now reality.