An epidemiologist is a public health professional who studies the patterns and causes of diseases. They conduct epidemiological studies to help understand, manage, and improve public health in a particular population. These studies help educate the public and influence decisions about best practices in treatment, resource allocation, and policy. They may work for government agencies, hospitals, and research institutions. Most epidemiologists specialize in a particular field of public health, such as infectious diseases, cancer, infant mortality, or substance addiction.