Emerging pervasive computing and communications technologies evolved into ample pioneering initiatives, leading towards a world in which computing systems are distributed, mobile, intelligent, supportive, unobtrusive, invisible and cooperative. Central to the notion of a pervasive systems is context-awareness. Context-aware computing endeavours to make systems aware of specific, relevant circumstances in the computing environment, and enable them to adapt their behaviour accordingly. Context-aware systems can process (intelligently) the context information acquired by any type of a sensor (either physical, computational or virtual). This, in turn, enhances services provided to users (including service personalization), makes pervasive systems smart by reacting (and possibly pro-acting) to changing circumstances, and enables adaptability and autonomy of systems, freeing users from avoidable sometimes routine interactions.