The etiology and ecology of diseases in populations are collectively referred to as epidemiology. This field studies the distribution, patterns, and causes of health and disease conditions in specified populations. Understanding both the biological and environmental factors influencing disease prevalence allows for better public health strategies and control measures. Key concepts include pathogen transmission, risk factors, and the impact of socioeconomic factors on health outcomes. Epidemiology is critical for identifying at-risk populations and developing effective interventions.