Here's why:

* Temperature and Color: A star's color is directly related to its surface temperature. Hotter stars emit more blue light, while cooler stars emit more red light.

* Spectral Classes: Astronomers classify stars based on their temperature and spectral lines. The coolest stars fall into the "M" spectral class, which are red.

* Examples: Red dwarfs are a common type of cool star, and they are quite reddish in appearance.

So, remember: Red = Cool, and Blue = Hot when it comes to stars!