Public Health 101: Healthy People Healthy Populations (2nd Edition) is an introductory textbook that explains the foundations of public health using a population-focused approach to health and disease. It explores how factors such as environment, behavior, healthcare systems, laws, and social conditions influence health outcomes across communities. The book emphasizes prevention, health promotion, and evidence-based strategies, helping readers understand how public health interventions improve the well-being of entire populations rather than just individuals.