Governments will always play a huge part in solving big problems. They set public policy and are uniquely able to provide the resources to make sure solutions reach everyone who needs them. They also fund basic research, which is a crucial component of the innovation that improves life for everyone.

There is this broad, broad recognition of how technology is enabling new things. Companies that never paid attention to computers in any form now see digital technology as creating threats and opportunities for them.

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.

I regret being the richest man in the world because that position attracts undeserved publicity.

There's nobody getting rich writing software that I know of.

Polio's pretty special because once you get an eradication, you no longer have to spend money on it; it's just there as a gift for the rest of time.

If we can find approaches that meet the needs of the poor in ways that generate profits for business and votes for politicians, we will have found a sustainable way to reduce inequity in the world. This task is open-ended. It can never be finished. But a conscious effort to answer this challenge will change the world.