Natural epidemics can be extremely large. Intentionally caused epidemics, bioterrorism, would be the largest of all.

We're responsible for the creation of the PC industry. The whole idea of compatible machines and lots of software - that's something we brought to computing. And so it's a responsibility for us to make sure that things like security don't get in the way of that dream.

I never took a day off in my twenties. Not one.

Security is, I would say, our top priority because for all the exciting things you will be able to do with computers - organizing your lives, staying in touch with people, being creative - if we don't solve these security problems, then people will hold back.

When you write a piece of software you assume a certain type of hardware. If you assume hardware that's too powerful then you can't sell many copies cause very few people have that machine. If you assume hardware that's too simple your product can't do as much.

Your most unhappy customers are your greatest source of learning.

Microsoft has had clear competitors in the past. It's a good thing we have museums to document that.