Although subsumed under various nomenclatures such as customization, personalization, and tailoring, the notion of matching media messages to individuals has attracted enduring attention from academia and industry. This talk, which is part of a book project, reviews a program of research on the psychology of customization in modern media environments. We discuss evidence from a series of studies that shed light on many nuances of customization, while also accentuating its deployment and applicability in diverse online venues (e.g., Web portals, news sites, e-commerce sites, health interfaces, virtual reality).