Astronomers group stars into classes according to spectral color and brightness.

Stars come in different types, and most stars will change types throughout their lifetimes. Stars are often organized using what's known as the Hertzsprung-Russell (H-R) diagram.

Stars like Earth’s sun that burn hydrogen into helium are in a group called the "main-sequence."

The sun is currently a type G, yellow, main-sequence star. In the future, the sun will run out of hydrogen, leave the main-sequence, and become a red giant. After it explodes into a nova, the sun will become a tiny white-dwarf star, surrounded by a planetary nebula.