Build what you want to see in the world.

I think that great programming is not all that dissimilar to great art. Once you start thinking in concepts of programming it makes you a better person...as does learning a foreign language, as does learning math, as does learning how to read.

The interesting products out on the Internet today are not building new technologies. They're combining technologies. Instagram, for instance: Photos plus geolocation plus filters. Foursquare: restaurant reviews plus check-ins plus geo.

Anything you're interested in the world whether it be Charlie rose or JetBlue or a public figure or your local coffee shop, they're on Twitter and broadcasting what is interesting to them.

It's a matter of invitations versus context. Twitter is really good at providing context, like, I''m having coffee at Third Rail Coffee.' Foursquare is about invitations to places. In this respect Foursquare has started to replace Yelp for me.

Everyone has an idea, but it's really about executing the idea and attracting other people to help you with the idea.

I think Twitter is the future of communications and Square will be the payment network.