With insight and verve, Griffin argues that innovation and best practices are discovered by the experimentation of entrepreneurs as they establish the evolutionary fitness of their business. The products and services created through this experimentation that have greater fitness survive, and less-fit products and services die. Entrepreneurs have always experimented when creating or altering a business. What is different today is the existence of modern tools and systems that allow experiments to be conducted more cheaply and rapidly than ever before. Griffin shows that listening to what the best venture capitalists have to say is invaluable for entrepreneurs. Their experiences, if studied carefully, teach bedrock methods and guiding principles for approaching business.