The colour of a star is directly related to its surface temperature. The hottest stars are blue.

Here's a simplified breakdown:

* Blue: Highest temperature (over 25,000 Kelvin)

* White: Very hot (around 10,000 Kelvin)

* Yellow: Moderate temperature (around 6,000 Kelvin)

* Orange: Cooler (around 4,000 Kelvin)

* Red: Coolest (under 3,500 Kelvin)

Think of it like a stovetop: The red-hot burner is cooler than the blue-hot burner.