The introductory note clarifies the thematic and historiographical framework within which the volume is situated by presenting DiplomatiCon, the project from which it derives, and identifying the main themes of the work. In a late medieval Mediterranean characterised as a space of contact and interaction, networks of individuals and groups are central. Social network analysis, conducted either qualitatively or using computational tools of varying complexity, is key to understanding the range of case-studies offered by the volume.