This chapter gives an overview of the broad range of interaction techniques for use in ubiquitous computing. It gives a short introduction to the fundamentals of human-computer interaction and the traditional user interfaces, surveys multi-scale output devices, gives a general idea of hands and eyes input, specializes them by merging the virtual and real world, and introduces attention and affection for enhancing the interaction with computers and especially with disappearing computers. The human-computer interaction techniques surveyed here help support Weiser’s idea of ubiquitous computing (1991) and calm technology (Weiser & Brown, 1996) and result in more natural interaction techniques than in use of purely graphical user interfaces. This chapter will thus first introduce the basic principles in human-computer interaction from a cognitive perspective, but aimed at computer scientists. The humancomputer interaction cycle brings us to a discussion of input and output devices and their characteristics being used within this cycle. The interrelation of the physical and virtual world as we see it in ubiquitous computing has its predecessors in the domain of virtual and augmented realities where specific hands and eyes interaction techniques and technologies have been developed. The next step will be attentive and affective user interfaces and the use of tangible objects being manipulated directly without using dedicated I/O devices.