It's empowering to be asked to look at what's possible, not told how to do it.

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.

A number of people in the United States, almost everyone, is using plastic cards to pay for things, but it's extremely difficult to accept these cards. So let's make it's easy and take more and more of the friction out as we can.

I spend 90% of my time with people who don't report to me, which also allows for serendipity, since I'm walking around the office all the time. You don't have to schedule serendipity. It just happens.

Your job as an executive is to edit, not write. It's OK to write once in a while but if you do it often there's a fundamental problem with the team. Every time you do something ask if you're writing or editing and get in the mode of editing.

You don't have to start from scratch to do something interesting. You don't have to start from scratch to have a massive impact on the world. You have to have a good idea. You have to convince other people of those good ideas. And you have to push as quickly as possible.

Twitter was around communication and visualizing what was happening in the world in real-time. Square was allowing everyone to accept the form of payment people have in their pocket today, which is a credit card.