About every year or two, there is a moment of truth where there's some new development in the marketplace, some new technology, some sort of existential crisis. You just have to be vigilant about looking out for those moments.

I think with every successful consumer Internet business, there will be lawyers that are interested in going after your company, especially when they think that there's a financial incentive.

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.

There are so many businesses that are succeeding on Yelp that don't pay us a dollar, and we're really excited about that.

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.

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

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.