Here's why:

* Color and Temperature: A star's color is directly related to its surface temperature.

* Blackbody Radiation: Stars emit light across a range of wavelengths, and the peak wavelength of this radiation corresponds to a specific color. Hotter objects emit more of their radiation at shorter wavelengths, which appear bluer.

* Blue to Red: As stars cool down, their peak emission shifts toward longer wavelengths, making them appear redder. So, the color progression goes from blue (hottest) to white to yellow to orange to red (coolest).