In a primer intended for the administrative professions, for the behavioral sciences, and for education, simulation and its various aspects are defined, illustrated, and explained. Man-model simulation, man-computer simulation, all-computer simulation, and analysis are discussed as techniques for studying object systems (parts of the "real world"). The role of models in simulation is examined. Computer systems, services, languages, and input output equipment are reviewed. An explanation of Monte Carlo techniques and their use in simulation is given. Applications of simulation are reported in almost every imaginable area: among others, computer systems, educational gaming, counseling, educational administration, communication networks, social systems, war and crisis gaming, operational gaming, management games, queuing systems, operations research and management science, business decision making, personnel problems, physical systems, continuous systems, and flight and space activities. (MF)