The Lean Startup asks people to start measuring their productivity differently. Because startups often accidentally build something nobody wants, it doesnt matter much if they do it on time and on budget. The goal of a startup is to figure out the right thing to buildthe thing customers want and will pay foras 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.

The Lean Startup by Eric Ries