Here's a simplified breakdown:

* Hot stars (around 30,000 Kelvin and above) appear blue or white.

* Medium-hot stars (around 7,500 to 10,000 Kelvin) appear yellow-white.

* Medium-cool stars (around 5,000 to 7,500 Kelvin) appear yellow.

* Cool stars (around 3,500 to 5,000 Kelvin) appear orange.

* Very cool stars (below 3,500 Kelvin) appear red.

This is because hotter objects emit more light in shorter wavelengths, which are perceived as blue and white, while cooler objects emit more light in longer wavelengths, which are perceived as red and orange.