Introduction.- Ambient Intelligence: A New Computing Paradigm and a Vision of a Next Wave in ICT.- Context and Context Awareness of Humans and AmI Systems: Characteristics and Differences and Technological Challenges and Limitations.- Context Recognition in AmI Environments: Sensor and MMES Technology, Recognition Approaches, and Pattern Recognition Methods.- Context Modelling, Representation, and Reasoning: An Ontological and Hybrid Approach.- Implicit and Natural HCI in AmI: Ambient and Multimodal User Interfaces, Intelligent Agents, Intelligent Behavior, and Mental and Physical Invisibility.- Towards AmI Systems Capable of Engaging in 'Intelligent Dialogue' and 'Mingling Socially with Humans'.- Affective Behavioral Features of AmI: Affective Context Aware, Emotion-Aware, Context-Aware Affective, and Emotionally Intelligent Systems.- The Cognitively Supporting Behavior of AmI Systems: Context Awareness, Explicit Natural (Touchless) Interaction, Affective Factors and Aesthetics, and Presence.- Concluding Remarks, Practical and Research Implications, and Reflections.