Artificial intelligence (AI) offers powerful new tools for addressing persistent public health challenges. Why should we use AI in the public health domain? This chapter introduces AI for a public health audience, providing clear definition—technical, role-based, conceptual, and ethical—and critically important limitations such as AI hallucination. Simultaneously, it outlines the core needs and complexities of public health for an AI audience, highlighting real-world application opportunities. The chapter presents the organization of the book, which is structured to guide readers from AI introduction (Part I), modeling of AI applications in public health (Part II), big data in public health (Part III), case studies (Part IV), living with AI (Part V), to futures (Part VI). By establishing this shared foundation and roadmap, the chapter prepares students, practitioners, policymakers, and AI developers to engage meaningfully with AI as informed users or designers of AI applications in the field of public health.