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.

We get to design what we want to see in the world rather than doing what other people think should be done.

I think Twitter is best when it sparks conversations elsewhere. To use YouTube and Facebook and all the tools we have available to us today to respond and also promote and answer and engage is awesome.

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.

An idea that can change the course of the company can come from anywhere.

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.

Make every detail perfect and limit the number of details to perfect.