I don't think of Twitter as a social network. I think of it as a messaging system that has a lot of social components to it.

I mean, even when it's really simple, there's so much amazing beautiful creativity that can come out of that.

In any leadership position, you're always going to be disappointing somebody.

At Twitter, mobile is in our DNA ... For us, it's all about mobile, and it always has been.

When a plane lands in the Hudson and there's a Twitter user on the ferry taking a picture of it, Boom. That's it. The water is still splashing. Here's the photo of the thing.

I started designing book jackets, which was great because I was good at it. And then from there I decided to become a freelance graphic designer and I needed to expand beyond book jackets, so I taught myself web design, and then in 1999 some friends of mine decided to start a company called Xanga.com, which was a very early kind of social network slash blogging community.

I thought I was going to stay at Google, because it was a great place to work.