Media is very different from financial services. People are very fickle and very vocal. They believe that things should be one way and not the other. It's still very rewarding to build products for huge audiences. It feels like you're making an impact.

The single most important top-level trend is the shift to mobile.

Right now, nearly all the apps on Facebook take a week to build. No more.

If I see what you're up to on Facebook but I don't see your updates on Flickr, I'll still care about Facebook.

Ignore your mistakes. The number one thing to worry about is -Am I doing what I'm good at?

The very first company I started failed with a great bang. The second one failed a little bit less, but still failed. The third one, you know, proper failed, but it was kind of okay. I recovered quickly. Number four almost didn't fail. It still didn't really feel great, but it did okay. Number five was PayPal.

If you're building a social product, you're still living in the last century if your product doesn't work on Facebook.