This introductory chapter of the book Healthcare Financing and Insurance: A Guide for Practitioner, Professionals, and Policymakers provides a foundational framework for understanding health systems and their financing mechanisms. It begins by defining the concept of a health system, outlining its goals and core functions. The chapter then explores the critical role of financing function of health system in achieving these goals, emphasizing the key functions of health financing—revenue collection, fund pooling, strategic purchasing of services, and service provision. Further, the chapter introduces various health financing models that have evolved historically and examines their relevance to the Indian healthcare landscape. The discussion also extends to the role of health financing in strengthening health systems, aligning with the Sustainable Development Goals (SDG), and advancing the agenda of Universal Health Coverage (UHC). By providing a comprehensive overview of health systems and role of health financing in health systems, this chapter lays the groundwork for the readers of the book, equipping them with the essential knowledge required to navigate and contribute to India’s evolving health financing landscape.