Giant stars are massive celestial bodies that have expanded and cooled after exhausting the hydrogen fuel in their cores. They are significantly larger than our Sun, often having diameters up to 100 times greater. These stars are typically classified into two main types: red giants and blue giants, depending on their temperature and color. As they evolve, giant stars undergo various stages, eventually leading to their death. Red giants may shed their outer layers, creating beautiful nebulae, while blue giants can explode in supernovae, leaving behind neutron stars or black holes. Their life cycles play a crucial role in enriching the universe with heavy elements, contributing to the formation of new stars and planets.