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.

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.

TweetDeck is a very interesting client, because it presents a view that no other client in the world presents, which is this multicolumn, massive amounts of information in one pane. And people really, really enjoy that.

Your job as an executive is to edit, not write. It's OK to write once in a while but if you do it often there's a fundamental problem with the team. Every time you do something ask if you're writing or editing and get in the mode of editing.

A number of people in the United States, almost everyone, is using plastic cards to pay for things, but it's extremely difficult to accept these cards. So let's make it's easy and take more and more of the friction out as we can.

Great companies don't just have one founding moment. They have many founding moments.

Success is never accidental.