This book is a groundbreaking exploration of N-heterocycles, encompassing their historical significance, current prospects, and diverse biological applications. The book's primary objectives are to unravel the historical evolution of N-heterocycles, elucidate their contemporary relevance, and investigate their crucial role in various scientific domains. This book fills a substantial knowledge gap by offering a holistic perspective on N-heterocycles, fostering a profound understanding of their diverse applications, inspiring future research directions, and serving as a vital educational resource. It employs a multifaceted approach, including historical analysis, literature review, case studies, and expert insights. Key findings include the appreciation of N-heterocycles' historical importance, exploration of their myriad biological applications, and insights into emerging trends in sustainable chemistry. While the book is not exhaustive due to the vastness of the field, its impact is significant, disseminating knowledge, inspiring innovation, and contributing to both research and practice in various scientific disciplines. This book emerges as a crucial reference, connecting the past, present, and future of these remarkable compounds and their interdisciplinary applications.