This book adopts a pluridisciplinary approach, drawing on fields such as linguistics, cognitive science, psychology, sociology and philosophy, in order to explore interaction with the help of complex systems theory. It is divided into seven chapters: The first two chapters focus on explaining complex systems theory and applying it to the interaction supercomplex adaptive system. Interaction is defined and the current approaches to studying it are discussed. Then a new idea, called the 4Es of interaction, is introduced. The 4Es offer a different way of thinking about interaction, which is in no way intended to limit interaction to an essentialist model, on the contrary, the 4Es are to be used in the most dynamic way to better grasp the supercomplexity of interaction.