What causes a star to evolve into a red giant?

Oh, look at that beautiful red giant in the sky, almost like a happy dancing soldier! A star evolves into a red giant as it nears the end of its life and starts to exhaust its core hydrogen fuel. As this happens, the star swells up and cools down, creating that lovely reddish hue we see. Just like in nature, stars too go through different seasons, celebrating each phase of their unique journey.