O, B, A, F, G, K, M Types

The O, B, A, F, G, K, M classification system categorizes stars based on their temperature and color. O-type stars are the hottest and brightest, appearing blue, while M-type stars are the coolest, looking red. In between, B-type stars are blue-white, A-type are white, F-type are yellow-white, and G-type stars, like our Sun, are yellow. Each type indicates the star's characteristics, including its size, lifespan, and how it evolves. This system helps astronomers understand stellar behavior and the universe's structure.