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.

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.

Pick a movement, pick a revolution and join it.

Meet customers where they are; question how to make the tools customers use more valuable.

You don't have to start from scratch to have a massive impact on the world.

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.

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.