In this chapter, we discuss how platforms manage the interaction between various users. First, we discuss and exemplify governance decisions by platforms that affect access and interactions of users regarding a platform service. Here, we investigate the choice of price structure and the choice of non-price strategies. We also address the horizontal and vertical scope of these platforms. Second, we consider platform decisions that generate spillovers to other platforms or channels, and we explore private incentives and welfare effects. Third, we discuss the role of government regulation in a broad sense, that is, the laws and regulations that constrain platforms and shape their incentives regarding their governance decisions. Emphasis is given to interventions against anticompetitive conduct and practices that may lead to consumer harm.