This book presents several original theories for risk, including Theory of Risk Monitoring, and Theory of Risk Acceptance, in addition to several analytical models for computing relative and absolute risk. The book discusses risk limit, states of risk, and the emerging concept of risk monitoring. The interrelationships between risk and resilience are also highlighted in an objective manner. The book includes several practical case studies showing how risk management and its components can be used to enhance performance of infrastructures at reasonable costs.