The stellar classification system is a method used by astronomers to categorize stars based on their temperature, color, and spectral characteristics. This system primarily uses a sequence of letters, with the main classes being O, B, A, F, G, K, and M, ranging from the hottest and most massive stars to the coolest and least massive ones. Each class is further divided into subclasses, allowing for a more detailed classification. The classification also includes a numerical scale that indicates the temperature of the stars within each class. For example, O stars are extremely hot, with temperatures exceeding 30,000 Kelvin, while M stars are cooler, with temperatures below 3,500 Kelvin. This system helps astronomers understand the life cycles, compositions, and evolutionary processes of different types of stars.