Health insurance is the mechanism used to respond to uncertainty and risk aversion to illness. Health insurance, whether private, public, or mixed, serves as the main structural foundation for health systems across countries. Its objectives are to minimize the financial burden of medical expenses on people and to enhance population health. Globally, there is a great diversity of health systems and even greater variation among them. There are substantial differences in health systems and health insurance between low- and middle-income nations. The primary explanation for this could be the disparities in the resources available to fund the health system. High-income countries have the financing ability to fund the provision of health care, whereas low- and medium-income countries have a harder time funding health care. Another challenge health systems face nowadays is the achievement of the United Nations Sustainable Development Goal 3: healthy lives and promoting well-being for all. To create resilient and sustainable health systems that guarantee healthy lives and foster well-being for people of all ages, many countries are redesigning their healthcare systems by improving financing, access, and coverage. This book discusses these issues in different health systems around the world, in low-, middle-, and high-income countries.