Stewart Butterfield

Email is the lowest common denominator. It's the way you get communications from one person to another. There isn't really an alternative. Sometimes people will have Facebook messenger turned on, but 99 percent of the time, if you're sending a message to a human you don't know well, you're using email.

The scale of revenue growth is unprecedented. If you look back over history, whether you're looking at the railway robber baron era or the 1920s or the '50s or the '70s, it used to take a long time for a company to get to the point where they had tens of millions of dollars of revenue. It was almost never an overnight phenomenon.

Every time you log in to Facebook, every time you click on your News Feed, every time you Like a photo, every time you send anything via Messenger, you add another data point to the galaxy they already have regarding you and your behavior.