The best marketing book I have read is "The Lean Start-Up: How Constant Innovation Creates Radically Successful Businesses" by Eric Ries. This book changed the way I think about marketing and businesses in general. Prior to reading this book, I thought that the only way to be successful in business was to have a great product or service and to have a lot of money to spend on marketing and advertising. However, this book taught me that there is a better way to do things. The Lean Start-Up methodology is all about constant innovation and continual improvement. This method can be used by businesses of all sizes, from start-ups to large corporations. This book is a must-read for anyone who is interested in marketing or running a business.