A supernova is a powerful explosion that occurs at the end of a star's life cycle. When a massive star exhausts its nuclear fuel, it can no longer support itself against gravity, leading to a dramatic collapse. This collapse causes the outer layers of the star to explode outward, releasing an enormous amount of energy and light, often outshining entire galaxies for a short time. Supernovae are important for the universe because they create and spread heavy elements, like gold and iron, into space. These elements eventually become part of new stars, planets, and even life forms, making supernovae crucial for the cosmic cycle of matter.