A comprehensive historical and conceptual review of public diplomacy is presented in this chapter, tracing its evolution from traditional state-to-public communication toward today's multidimensional and networked practices. The discussion examines how public diplomacy has been theorised across international relations, communication studies, soft-power analysis, and networks diplomacy. Particular attention is devoted to Educational Diplomacy as an influential yet unevenly utilised dimension of public diplomacy. The analysis demonstrates how some states successfully transformed educational exchange, academic partnerships, and scholarship programs into long-term instruments for building trust, strengthening national reputation, and encouraging intellectual understanding. At the same time, it highlights why other states failed to capitalise on these opportunities. By contrasting these experiences, the chapter establishes the brother theoretical foundation for understanding why educational diplomacy becomes transformative for some countries while remaining constrained or ineffective for others.