The book "Intelligent Agents" offers a comprehensive examination of agent theory and its adaptation in various contexts. It highlights the necessity for agents, regardless of their complexity, to operate autonomously within the rules they use. A central theme is the agents' ability to recognize rules from the available data through their "brains." These rules are crucial for the agents' alteration of their environment, and any modification of these rules is viewed as an evolution of the agents. The book addresses the challenges of uncertainty in different contexts and demonstrates how global uncertainty can be integrated into the description of the rules. With ten chapters ranging from a general description of evolutionary adaptive agents to practical applications in robotics and evolutionary computing, it provides a solid foundation for understanding and developing intelligent agents.