A giant star is a type of star that is significantly larger and more luminous than the Sun. These stars have expanded in size after exhausting the hydrogen fuel in their cores. They can be classified into two main categories: red giants and blue giants, depending on their temperature and color. Giant stars are often found in the later stages of stellar evolution. They can eventually shed their outer layers, leading to the formation of a planetary nebula or a supernova, depending on their mass. The remnants can become a white dwarf or a neutron star.