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

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

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.

When Yelp first took off, our rankings on Google would fluctuate wildly.

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

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.

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.