This chapter focuses on the role of communication in science and medicine, the scope of scientific and medical communication, genres, audiences, and discourse communities in science and medicine and limitations of the scientific research method and the resulting influence on communication. It examines the major genres of scientific and medical communication (SMC), distinguished between primary and secondary sources, and discusses the needs and reading patterns of the audiences. Scientific information is knowledge that arises from systematic observation or experimentation, which is referred to as the scientific method. In SMC, journal editors and peer reviewers serve as gatekeepers by evaluating journal articles prior to publication. Conference posters and presentations have gatekeepers but undergo a less stringent peer-review process often based on a summary of the research presented in an abstract. Since the only genre undergoing the complete peer-review process is journal articles, that is the only genre that should be credited and cited as the primary source of original research findings.