Luminescence is the emission of light by a substance that has not been heated. This phenomenon occurs when certain materials absorb energy and then release it as visible light. It can happen in various forms, including fluorescence, where light is emitted almost immediately after energy absorption, and phosphorescence, where the light is emitted over a longer period. Luminescence can be found in nature, such as in fireflies and certain types of fungi, as well as in artificial applications like LEDs and glow-in-the-dark materials. It plays a significant role in fields like biology, chemistry, and technology, providing insights into various processes and enhancing visual displays.