Introduction to Intelligent Simulation of Complex Discrete Systems and Processes: RAO Language focuses on a unique approach in modeling and simulation of complex systems. In this volume are considered features of complex systems and processes, their mathematical description, and modeling. Theoretical foundations of the RAO (Resource-Action-Operation) language as well as its syntax and utilisation are given. Examples of simulation models of different complexity levels, related to different fields, are also presented. The RAO intelligent modeling system, introduced and described in Introduction to Intelligent Simulation of Complex Discrete Systems and Processes is unique because: (1) it makes simulation modeling universal for the classes of systems and processes modeled; (2) it is simple to modify the models; and (3) it has the capacity to model complex control systems together with the object controlled (including simulation modeling for on-line control). The RAO tool allows the user to use a language very similar to his professional language and rids him of intermediary, supplementary description of the system modeled. In fifteen chapters this volume provides an overview of general modeling trends, and hence serves the research community in guiding their modeling methods; intelligent simulation modeling is introduced to solve complex systems and processes.