The AMA represents medical doctors and medical students in the United States. The mission of the AMA is "to promote the art and science of medicine and the betterment of public health." The AMA is organized into various groups: Membership, Publishing & Business Services, Core Operations, Administration and Operations, and Affiliated Organizations. The AMA publishes the Journal of the American Medical Association (JAMA), which has the largest circulation of any weekly medical journal in the world. The AMA publishes a list of Physician Specialty Codes, which are the standard method for identifying physician and practice specialties in the United States.