This idea of, there's a locked door; how do you open it? You don't necessarily care what's behind it; you're just more excited about opening the lock... It's not about finding the treasure; it's more about defeating the puzzle.

When you walk into a field office, you have many opportunities. We'll hand you a call sheet. You can make calls. You can knock on doors, and they'll have these stacks there for you. They'll say: 'Harper, you've knocked on 50 doors. That's great. Here's how you compare to the rest of them.' But it's all very offline.

Mobile usage is going up; mobile conversion is not.

Before I was hired by Obama's team as the CTO for his 2012 re-election campaign, I had certainly never been involved with anything of that nature before. Yet, I somehow knew I could do the job. I attribute that confidence to my experience as a hacker and the subsequent willingness to take risks.

I think there are a lot of hurdles between a normal consumer brand figuring out their mobile strategy - let alone their chat app strategy - and programming a Facebook Messenger chatbot.

I try and wake up relatively early. I listen to some music and check Twitter. I also make sure I weigh myself and check how long I slept. I do that because knowing that data seems better than not knowing it.

You can tell charlatans when they say 'big' in front of everything.

First of all, a giant corporation probably shouldn't be being hacked by teenagers. I put that on the corporation, not the teenagers. Teenagers are going to do what teenagers are going to do - rebelling. But if they're able to hack a big corporation, that seems like the corporation should be better at security.

We were orbiting around the idea of intent and context. We would take the bus into work, and if you said, 'Here's a shirt you might like,' and I open it on my mobile phone, I'm not going to pull out my credit card and wallet. We thought, 'How does someone do this? An e-mail to yourself, or you try to remember?'

Books have literally powered most of my life. Whether as a stress relief when doing hard things or as vacation fodder, they are a constant and important part of my life.

The digital team who were running Twitter, they weren't just going to put out a tweet for fun. They're going to try and figure out how do we measure the impact. Then they'd tweet it, and if it worked, great.

Chicago's a flyover city. I don't think we should try to change that. But it would be really cool if we had a little more opportunity for investors to come hang out.

I would still describe myself as a hacker. I still remember feeling the magic, the sense of discovery, when I first connected to a bulletin board. It seemed like the world was somehow brighter, the greens were greener. Like I'd stepped through a portal to the other side. I knew back then that things would never be the same again for me.