Stellar classification is the process of categorizing stars based on their observed characteristics, such as temperature, luminosity, and spectral features. This classification system helps astronomers understand the different types of stars in the universe and how they evolve over time. The most common classification system for stars is the Morgan-Keenan (MK) system, also known as the Harvard Spectral Classification system. This system categorizes stars into seven main types based on their spectral features: O, B, A, F, G, K, and M. Each of these types is further subdivided into subclasses based on more specific spectral characteristics. Stellar classification is important because it helps astronomers determine a star's properties and evolutionary stage, which in turn allows them to study the formation and evolution of galaxies, star systems, and the universe as a whole. It is also essential for identifying potential candidates for further study, such as exoplanets or objects of interest for astrobiology.