When public health comes into the question, along with it comes the question of the study of people in a selected population group, their health, and disease conditions to precisely measure the state of the public health in that particular area. Epidemiology is the study and analysis of the distribution and determinants of health and disease conditions in a given population. Epidemiology plays a major role in policy-making based on the study of risk factors, statistical analysis of decades of data, and research in life sciences. Major areas of this study include the investigations on causes, transmission, outbreak, and surveillance studies to an extent till where they draw appropriate conclusions to bring out solutions, amends, and ways to prevent, cure and eradicate and even eliminating the possibility of re-occurrence of such an incident again. Epidemiology is the keystone of public health, it’s implementation and progress.