“The Lean Startup: How Constant Innovation Creates Radically Successful Businesses” is a book written by Eric Ries. It is a guide for entrepreneurs on how to build and grow a successful startup by using the “lean startup” approach.

The lean startup approach is based on the idea that startups can achieve success by iteratively testing and refining their business model. The approach involves constantly gathering customer feedback, measuring progress, and adapting based on what is learned. This allows startups to quickly identify and address problems, and avoid the common pitfalls that lead to failure.

In the book, Ries provides a step-by-step guide for implementing the lean startup approach. He covers topics such as how to validate business ideas, how to build and measure progress, and how to scale a successful business. The book also includes a number of case studies and examples to illustrate the concepts in action.

Overall, “The Lean Startup” is an informative and practical book that offers valuable insights for entrepreneurs looking to build and grow a successful startup. It is well-written and offers a number of helpful tools and strategies for avoiding common pitfalls and achieving success.