There is this cat and mouse game that plays out over time where our team comes up with new and interesting ideas to identify content that we shouldn't recommend, and over time people are constantly probing that, trying to figure out how can they get around that and get a better reputation on Yelp.

Maintaining the trust of the consumer is critical to our business. We live and breathe only one thing, which is wanting to connect consumers with great local businesses, and I don't feel we can do that if we don't have effective ways to prevent gaming of the system.

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.

Theres simply anger over the accountability that Yelp brings and also this feeling of powerlessness because so much power is now being put in the hands of the consumer. But the important thing that gets lost with some of these business owners who are very upset with us is its the whole picture that counts.

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.

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.

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