Fluorescence is a process where certain materials absorb light at one wavelength and then emit it at a longer wavelength. This phenomenon occurs when the absorbed energy excites electrons in the material, causing them to move to a higher energy state. When the electrons return to their original state, they release energy in the form of visible light. Common examples of fluorescence include fluorescent lights, which use this principle to produce bright light, and fluorescent dyes, often used in biological research to label cells. Fluorescence is also utilized in various applications, such as forensic science and medical imaging.