We must learn what customers really want, not what they say they want or what we think they should want.

Entrepreneurs can't forecast accurately, because they are trying something fundamentally new. So they will often be laughably behind plan - and on the brink of success.

The goal of a startup is to figure out the right thing to build-the thing customers want and will pay for-as quickly as possible. In other words, the Lean Startup is a new way of looking at the development of innovative new products that emphasizes fast iteration and customer insight, a huge vision, and great ambition, all at the same time.

Vanity metrics are the numbers you want to publish on TechCrunch to make your competitors feel bad.

If you don't know who your customer is, you don't know what quality is.

At IMVU, the cost of customer acquisition through our five-dollar-a-day AdWords campaign was less than twenty-five cents. Our revenue from those same customers was more than a dollar.

New Customers come from the action of past customers