ChatGPT, as a major leap in the field of artificial intelligence, has stirred widespread discussions, and its powerful functionality is closely tied to the support of large-scale models. This book focuses on large-scale models, providing a detailed account of their technical scenarios and commercial applications. Starting with the typical application ChatGPT, this book explores the allure behind the underpinning of large-scale models. Firstly, the book explains the fundamental concepts of large-scale models, industry landscape, and the emergence of new business models, showcasing the current development status and commercial potential of large-scale models. Secondly, the book delves into numerous application scenarios of large-scale models, such as data services, intelligent search, office tools, conversational AI, leisure and entertainment, manufacturing, smart marketing, and smart cities, elucidating the current application status, potential, and enterprise exploration practices in these domains.