Why are some stars hotter than others?

Some stars are hotter than others primarily due to their mass and stage in the stellar lifecycle. More massive stars have greater gravitational pressure at their cores, leading to higher temperatures and increased nuclear fusion rates. Additionally, the composition of a star can influence its temperature; for example, stars with higher metallicity can have different fusion processes. Finally, a star’s age and the energy it produces through fusion also play significant roles in determining its surface temperature.