I'm less interested in how people are following each other and more interested in how they are following topics and tweets themselves. People are following more key words and concepts and more ideas and acting on those rather than individuals or organizations.

Twitter has been my life's work in many senses. It started with a fascination with cities and how they work, and what's going on in them right now.

Build what you want to see in the world.

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.

As CEO, my main job is editor-in-chief.

Constraints inspire us in how we approach the press, how we approach business relationships, how we do everything.

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.