This book progressively builds up the functional complexity of system modeling. It starts by modeling the simplest system that can be designed, and then moves to the functional modeling of the multi-state system, step-by-step. Reliability-based Modeling of System Performance deals with modeling the functioning of systems by presenting its concepts, methods and mathematical tools. It is accessible to engineering students and academics who have already acquired basic knowledge of probability theory, applied statistics, differential calculus, integrals, combinatorial calculus and Boolean algebra.