Since the initial inception of this book, there have been significant strides to safeguard the operations of our world’s infrastructures. In recent years, there has also been a shift to more fluid postures associated with resilience and the establishment of redundant infrastructure. In keeping with the fast-changing nature of this field, Critical Infrastructure: Homeland Security and Emergency Preparedness, Third Edition has been revised and updated to reflect this shift in focus and to incorporate the latest developments. The book begins with the historical background of critical infrastructure and why it is important to society. It then explores the current trend in understanding the infrastructure’s sensitivity to impacts that flow through its networked environment. Embracing an "all-hazards approach" to homeland security, critical infrastructure protection and assurance, and emergency management, the authors examine: The National Response Framework (NRF) and how it can be applied globally The relationships between the public and private sectors, and the growing concept of public-private partnerships The shift from the need-to-know paradigm to one based on information sharing, and the nature of necessary controls as this shift continues The need for organizations to adopt resilient planning, implementation, and decision-making processes in order to respond to changes within the threat environment What, where, why, and how risk assessments are to be performed, and why they are needed The impact of new regulation, individually applied self-regulation, industry and government regulation, and law enforcement In the final chapters, the book discusses current information sharing and analysis centers (ISACs), distributed control systems, and supervisory control and data acquisition (SCADA) systems and their challenges. It concludes by exploring current challenges associated with establishing a trusted network across various sectors—demonstrating how models of information can be categorized and communicated within trusted communities to better assure the public-private relationship.