Choose something you are passionate about - or a pain point that has affected you and that you feel really needs to be changed.

Maintaining the trust of the consumer is critical to our business

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.

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

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.

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.

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