The stars are massive celestial bodies made mostly of hydrogen and helium that produce light and heat through nuclear fusion. They are found in the universe, scattered across galaxies, and vary in size, brightness, and color. Our closest star, the Sun, is essential for life on Earth. Stars are born in clouds of gas and dust, known as nebulae, and go through various life stages, including main sequence, red giant, and supernova. After their life cycle, they can become white dwarfs, neutron stars, or black holes, depending on their mass.