"The Product Book," a book that provides practical advice and guidance on becoming a great product manager. The book is written by Josh Anon and Carlos González de Villaumbrosia, two experienced product managers, and it covers a wide range of topics, from understanding customer needs to validating product ideas, working with design and engineering teams, and finally launching and marketing the product. The text itself specifically focuses on the initial phases of product development, outlining the steps involved in finding the right opportunity, creating a hypothesis, validating it through various methods including customer development and A/B testing, and then using this validated information to create a product roadmap and PRD (Product Requirements Document).