Cool stars are a type of star that have lower surface temperatures compared to hotter stars like O-type and B-type stars. They typically fall into the K and M spectral classes, with temperatures ranging from about 2,500 to 5,200 degrees Celsius. These stars are often red or orange in color and can be found in various stages of their life cycle, including main sequence and giant phases. One of the most well-known cool stars is Proxima Centauri, which is the closest star to our solar system. Cool stars are important for studying the formation of planets, as they often have stable environments that can support the development of life. Their long lifespans also provide valuable insights into stellar evolution.