This chapter sets the stage for understanding the profound impact of digital communication tools on multilateral diplomacy, with a particular focus on WhatsApp. It explores the historical evolution of diplomatic communication, from traditional messengers to real-time messaging, and highlights the growing importance of mobile applications in facilitating coordination among diplomats. The chapter introduces the rationale for studying WhatsApp as a research subject, emphasizing its accessibility, informality, and increasing use in formal diplomatic contexts. It also outlines the methodology adopted in the book and presents the core questions guiding the research. The reader is introduced to the stakes involved in integrating instant messaging into professional diplomacy, including how it changes communication speed, hierarchy, and decision-making processes. Overall, the chapter lays the conceptual and practical foundation for examining WhatsApp’s role as both a technological and sociopolitical tool in diplomacy.