Multi-agent systems are already a focus of studies for more than 25 years. Despite substantial effort of an active research community, modeling of multi-agent systems still lacks complete and proper definition, general acceptance, and practical application. Due to the vast potential of these systems e.g., to improve the practice in software and to extent the applications that can feasibly be tackled, this book tries to provide a comprehensive modeling language - the Agent Modeling Language (AML) - as an extension of UML 2.0, concentrating on multi-agent systems and applications.