"As computing continues to become more powerful, more affordable and more connected it will give billions more people around the world a chance to take advantage of incredible new social and economic opportunities so they can lead better lives. And that will truly be revolutionary." With those words, Steve Ballmer has been telling attendees at CeBIT in Germany about what he calls the "Fifth Revolution" in computer technology. But what were the first four?

Computing Revolution #1 was  when the PC became affordable to all

Computing Revolution #2 was the emergence of the GUI, making computers easier to use for users

Computing Revolution #3 was the advent of the Internet and the WWW 

Computing Revolution #4 was the emergence of the Web as platform vs static HTML pages 

In his 28 years at Microsoft he has lived through all four of computing revolutions, said Ballmer. "But they have simply been a foundation for the much more profound changes to come in the next revolution," he added.

He went on to describe the Fifth Revolution from a Redmond, WA, perspective.