In space or astronomy, there are different stars, like our sun. Other stars may be bright, dim, big small and other physical characteristics. And the arrangement and study on what types of stars are in space is called Stellar Classification.
Stellar Classification is defined as the study of the stars, based on its heat capacity, color and age. In classifying these types of stars, the first step astronomers find out is hydrogen conversion speed and capacity, followed by analyzing the second layer of the star, or the chromosphere, and analyzing the light that the star is giving.
Stellar Classification has different levels: O, B, A, F, G, K and M types in this specific order. O Class stars are being considered as the hottest type of star, and the M class stars are coolest type of star. Each class also has a specific color assigned to it, and it is based on what color the star is currently. O class is of blue color, B type refers to bluish-white, A category pertains to white, F means Yellow-White, G group is of yellow color, K types point to orange stars and M class stars or of red color.
Also, each of these classifications refers to how hot and how much heat is being produced by the said star.