The central approach of microsociology is that social structures have their foundation in the concrete actions of specific individuals. The guiding assumption is that what occurs in interactions, in our everyday as well as extraordinary actions in various situations, is not random, arbitrary, or solely individual. Rather, a multitude of structures can be identified, consisting of patterns that transcend the uniqueness of each specific interaction event. This introduction provides the conceptual tools for analyzing processes of structural formation in interactions. It addresses aspects that precede each concrete interaction, whether they are universal mechanisms from which interaction cannot escape, or society-specific structures.