Interaction is a fundamental dimension for modelling and engineering complex computational systems. More generally, interaction is a critical issue in the understanding of complex systems of any sort: as such, it has emerged in several well-established scientific areas other than computer science, like biology, physics, social and organizational sciences.

In this chapter, we take a multidisciplinary view of interaction by drawing parallels between researches outside and within computer science. We point out some of the basic patterns of interaction as they emerge from a number of heterogeneous research fields, and show how they can be brought to computer science and provide new insights on the issue of interaction in complex computational systems.