Research shows that there is only half as much variation in student achievement between schools as there is among classrooms in the same school. If you want your child to get the best education possible, it is actually more important to get him assigned to a great teacher than to a great school.

With tech companies, whoever's the leader is always questioned, you know. They say, 'Is this the end of them?' And - there's more - more times people think that's the case than it really is the case.

Computers are great because when you're working with them you get immediate results that let you know if your program works. It's feedback you don't get from many other things.

There's always been a lot of information about your activities. Every phone number you dial, every credit-card charge you make. It's long since passed that a typical person doesn't leave footprints.

When Paul Allen and I started Microsoft over 30 years ago, we had big dreams about software. We had dreams about the impact it could have.

Now, we put out a lot of carbon dioxide every year, over 26 billion tons. For each American, it's about 20 tons. For people in poor countries, it's less than one ton. It's an average of about five tons for everyone on the planet. And, somehow, we have to make changes that will bring that down to zero.

Getting ready for a global pandemic is every bit as important as nuclear deterrence and avoiding a climate catastrophe.