There are, however, exceptions. Red giants and super giants are brighter than other stars of the same temperature because they are also bigger. Other stars, called white dwarfs, are fainter than stars of the same temperature because they are only about the size of planet earth. Giants, supergiants, and white dwarfs are all end points in the lives of stars, and the particular fate of a star depends on its mass. Despite its importance to us, the sun is only an average star.
Many stars are lighter than it is and many others are much more massive.
Stars about the same size as our sun end up as red giants. As such a star ages and uses up its fuel of hydrogen, the star cools and contracts, then heats up again and expands, growing into a red giant. Stars twice as heavy as the sun may grow even bigger, becoming a supergiant and may eventually explode into a supernova. Supernovae are so spectacular that they may approach and even exceed in brightness the whole galaxy in which it explodes. Unfortunately, modern astronomers and casual stargazers have not yet had the pleasure of watching a star blow up in the Milky Way.