Red giants are stars that have exhausted the hydrogen in their cores and now fuse helium and heavier elements. This process causes them to expand significantly and cool, resulting in their characteristic red color. They can be up to 100 times larger than the Sun, marking an important phase in stellar evolution. The lifespan of a red giant depends on its mass. Massive red giants may end as supernovae, while smaller ones shed their outer layers and become white dwarfs. Red giants also enrich the interstellar medium with heavier elements, contributing to the formation of new stars and planets.