Parasitology is a dynamic and essential field of biology that delves into the intricate relationships between parasites and their hosts. This book is designed to provide a comprehensive insight into parasitic organisms, detailing their life cycles, disease-causing mechanisms, and their effects on both human and animal health. Parasites are remarkably adaptable and resilient, having developed sophisticated survival strategies over time. Their ability to evade immune responses, influence host behavior, and develop resistance to treatments underscores the importance of parasitology in biomedical research, epidemiology, and public health. This book is structured to systematically explore key parasitic groups, including protozoa, helminths, and arthropods. Each chapter provides in-depth discussions on their biological characteristics, transmission patterns, pathological effects, diagnostic approaches, and control strategies. Special focus is given to vector-borne diseases, emerging zoonotic parasites, and the latest scientific advancements in molecular parasitology and disease prevention.