Effective written communication requires the author to consider the intended message and audience and use a form appropriate to both. Medical journal articles usually fit into one of the following 7 main types. Published reports of original research are the backbone of medical and scientific communications. Critical evaluation and replication of the findings of such reports are key aspects of quality control and progress in science and medicine; the clinical applications of original research are a major source of benefits for patients. Journals often categorize reports of original data as Original Articles, Original Communications, or Original Reports, section headings that emphasize the new findings such articles intend to communicate. Short articles reporting original data may be called Brief Reports. Studies that address basic issues of physiology or pathology may be called Research Reports or Clinical Investigations. In JAMA, articles that report preliminary findings are called Preliminary Communications...