Luminescent materials are substances that emit light when they are energized. This process can occur through various mechanisms, such as photoluminescence, where materials absorb light and then re-emit it, or chemiluminescence, which involves a chemical reaction. Common examples include glow-in-the-dark stickers and certain types of LEDs. These materials have a wide range of applications, from decorative items to safety signs that glow in the dark. They are also used in scientific fields, such as bioluminescence research, where organisms like fireflies and certain jellyfish produce light naturally. Luminescent materials play a crucial role in enhancing visibility and aesthetics.