The biggest thing is to create a product that consumers find useful. As more and more people like something, it becomes harder and harder to have a conspiracy theory about it.

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.

In the very beginning, Yelp started as a service where we really didn't think people would write reviews for fun. The whole concept of user-generated content was pretty nascent in 2004.

The biggest thing is to create a product that consumers find useful. As more and more people like something, it becomes harder and harder to have a conspiracy theory about it.

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.

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.

One of the challenges of buying local advertising is, how do you know if it worked? How do you know if it's got value? We're moving toward an e-commerce experience for local, an Amazon-like experience for local.