The main thing that's missing in energy is an incentive to create things that are zero-CO2-emitting and that have the right scale and reliability characteristics.

Melinda [Gates] has been my partner in raising the kids and I went from before I met her, intentionally having an unbalanced life, to having a more balanced life with all sorts of fun things that she and I do together.

When I was trying to figure out why lives have improved so much in the last 300 years, where we've gone from a third of kids dying before 5 to - by 1990 it was down to 10% - now it's down to 5%. And saying why, over all history, there were smart people, but that number didn't change. Average life span didn't change. What's magical about what's been deemed the Industrial Revolution? It's really energy intensity.

Software is inherently complicated. If you say to somebody I want an airline reservation system, to really say what you want in terms of overbooking and fares, and different airlines communicating with each or schedule changes, it's immensely complex. And so you can't write a program that's any simpler than that full specification.

Robotics and other combinations will make the world pretty fantastic compared with today.

My experience of malaria was just taking anti-malarials, which give you strange dreams, because I don't want to get malaria.

Microsoft is not about greed. It's about innovation and fairness.