Have confidence in your ideas before they even exist.
Creativity comes from constraint.
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.
Even the simplest tools can empower people to do great things.
We hired a CSR person at Twitter, years before we hired our first sales person, to make sure we had a culture and impact of doing good.
The future of marketing is philanthropy.