A fluorescent lamp is a type of electric light that uses a gas-filled tube to produce light. Inside the tube, a small amount of mercury vapor emits ultraviolet light when an electric current passes through it. This ultraviolet light then excites a phosphor coating on the inside of the tube, causing it to glow and produce visible light. Fluorescent lamps are commonly used in homes, offices, and schools due to their energy efficiency and long lifespan compared to traditional incandescent bulbs. They come in various shapes and sizes, including the familiar long tubes and compact versions known as CFLs (Compact Fluorescent Lamps).