Explore the fascinating world of red supergiants in this comprehensive lecture on dying stars. Delve into the differences between red supergiants and red giants, examine the HR and KipHan diagrams, and understand the importance of these celestial objects. Learn about the challenges in measuring red supergiant temperatures and atmospheres, and discover the observational evidence for their existence. Investigate their role in binary systems, including interactions and populations. Gain insights into synthetic models, composite SEDs, and future research directions. Understand the significance of red supergiants in studying supernova progenitors, massive stars, and their applications in upcoming space telescope missions. Examine near-IR spectra, transmission throughput curves, and potential James Webb observations. Conclude with a summary of key points and the latest developments in this exciting field of astrophysics.