We stand at a pivotal moment in the relationship between human ingenuity and the planetary systems that sustain us. The 20th century's chemical revolution bestowed upon society unimaginable advancements life-saving pharmaceuticals, high-performance materials, and the very fabric of modern convenience. Yet, this progress has been shadowed by a legacy of unintended consequences: environmental degradation, resource depletion, and the pervasive presence of hazardous substances in our ecosystems and our bodies. The traditional paradigm of chemical synthesis, often characterized by its linear "take-make-dispose" approach and its tolerance for inefficiency and hazard, is no longer tenable. The call for a fundamental transformation is not merely an environmental plea; it is an urgent scientific, economic, and ethical imperative.This book, Green Synthesis: Principles and Applications, is a direct response to that call. It is conceived not as a peripheral text on sustainability, but as a core reference for the next generation of chemical innovators the PhD researchers, postdoctoral scholars, and advanced academics who will design the molecular foundations of a sustainable future.