This introduction presents an overview of some key concepts discussed in the subsequent chapters of this book. The book introduces how public health principles may be applied during humanitarian contexts and responses to natural disasters. It focuses on how some essential public health tools and processes can be put into practice. The book describes the various public health approaches and principles that are relevant to the understanding of medical and public health disaster and humanitarian response. It explores the key concepts and trends of disasters and their implications for the twenty-first century. The book examines the human health impact of common natural disasters, and provides an overview of how health-related survival needs in natural disasters may be addressed. It also explores the public health threats and challenges for disaster medical response in the twenty-first century. The book also examines the role of key stake-holders and the challenges in public health response to disasters post-millennium.