How does an H R diagram compare stars?

An H-R (Hertzsprung-Russell) diagram compares stars based on their luminosity (brightness) and temperature (color). The horizontal axis typically represents temperature, decreasing from left to right, while the vertical axis represents luminosity, increasing from bottom to top. This diagram reveals patterns in stellar evolution, categorizing stars into groups such as main sequence, giants, and white dwarfs, and helps astronomers understand the relationships between a star's mass, age, and evolutionary stage.