The focus of the book is on completed implementations of agent-based software systems. Here, agent technology is considered broadly, starting from development of agent platforms, all the way through systems actually implemented. The covered topics also include lessons learned during implementation of agent platforms and the reflection on the process of development and application of agent-based systems. The book includes 10 chapters where interested reader can find discussion of important issues encountered during development of well-known agent platforms such as JADE and Jadex as well as some interesting experiences in developing a new platform that combines software agent and Web Services. Furthermore, the book shows readers several valuable examples of applications based on multi-agent systems including simulations, agents in autonomous negotiations and agents in public administration modelling.We believe that the book will prove useful to the researchers, professors and the practitioners in all disciplines including science and technology.