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

Maintaining the trust of the consumer is critical to our business

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.

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.

Starting a company, your success is going to be very dependent on how you adapt. You're going to make decisions, you're going to make bets; most of them are going to turn out to be wrong.

The entrepreneurs that really make it are the ones that start with an idea but are ready to change it at a moment's notice.