Community health is a subject of study within the medical and clinical sciences which focuses on population groups and communities as opposed to individual patients. It is a distinct field of study that may be taught within a separate school of public health or environmental health. Community health may be studied within three broad categories: The success of community health programmes relies upon the transfer of information from health professionals to the general public using one-to-one or one to many communication (mass communication). The latest shift is towards health marketing.