Luminescence

Luminescence is the emission of light from a substance that has absorbed energy, without the need for heat. When molecules or atoms absorb energy—such as from sunlight, electricity, or chemical reactions—they become excited and later release that energy as visible light as they return to normal. This process occurs in various forms, like fluorescence (quick emission), phosphorescence (delayed glow), and bioluminescence (biological light, like fireflies). Luminescence is used in everyday applications such as glow-in-the-dark objects, LED lighting, and medical imaging, highlighting its importance in science and technology.