Everyone has an idea, but it's really about executing the idea and attracting other people to help you with the idea.

Pick a movement, pick a revolution and join it.

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.

There's an entire universe in every single tweet, and it all really depends on the content as far as how it's going to spread.

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.

It's a matter of invitations versus context. Twitter is really good at providing context, like, I''m having coffee at Third Rail Coffee.' Foursquare is about invitations to places. In this respect Foursquare has started to replace Yelp for me.

Making something simple is very difficult.