It's really complex to make something simple.

What's interesting about Twitter and the influencers that someone follows - like, say, Shaquille O'Neal - is that they see someone who is using the exact same tools that they have access to, and I think that inspires this hope to be able to really engage with someone like him.

My mom cares that I tweeted a picture of my breakfast. She's knows I'm eating and I'm safe.

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

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.

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.

I love cities, and I love city governments in particular. But in politics it would have taken me 8 years from implementing a policy before I would get to see the feedback. With programming I could model the same policies and see the impact immediately. Technology is a far more efficient way to test.