The book "Human and National Security: Understanding Transnational Challenges" looks at how different threats like climate change, terrorism, and cyber attacks can affect people and communities worldwide, not just within one country. The authors argue that what keeps people safe also keeps countries safe in today's globalized world. The updated second edition discusses new issues like identity politics and how different groups work together to protect human security. This book is important for students studying security and international relations, as it shows how governments and societies can work together to create a safer world for everyone.