Nanosensors enable early diagnosis of various conditions with enhanced selectivity and sensitivity thus facilitating prompt initiation of therapy. This book introduces the readers to the basic concept of a nanosensor; the working of different nanosensors based on electrochemical, optical, magnetic, ultrasound, and hybrid sensing; and their varied applications in the healthcare field. This book highlights the regulatory aspects of nanosensors and the prospects of nanosensors in healthcare. The objective is to give the readers an overview of the possibilities and advances in the field. This book would provide deeper insights into designing nanosensors for precise diagnosis of various diseases.