Yelp is in a very nice spot: local data, and especially review data, is one of the killer apps on mobile phones.

If somebody writes a review of a dry cleaner, that piece of content is not wildly viral. It's not like a viral video that can spread across the world in a matter of minutes, so as a result, each market is almost an island unto itself.

You have to be very nimble and very open minded. Your success is going to be very dependent on how your adapt.

Everyone is panicked about the transition to mobile. I don't lose any sleep whatsoever.

Consumers are empowered by Yelp and tools like it: before, when they had a bad experience, they didn't have much recourse. They could fume, but often nothing else other than tell their friends.

In early 2008, it was confirmed that there would be an opportunity to build applications for the iPhone. We were fortunate enough to make the right call on that: to bet early, to put resources into it and have a pretty good application in the store at the moment when it opened.

A lot of what Groupon is generating is demand for something people didn't know they wanted.