T8 lamp is a fluorescent lamp (or fluorescent lamp, fluorescent tube, fluorescent tube) of a diameter of 1 inch, about 25 mm, is a kind of gas discharge lamp.

It uses electricity to activate mercury vapor in argon or neon to form a plasma and emit short-wave UV light, causing the phosphorous to emit visible fluorescence for illumination. Fluorescent tubes are generally made of glass, with sockets at both ends to connect the power and fix the position of the fluorescent tubes.

Unlike bulbs, fluorescent tubes must have a ballast (also known as a "ballast") that works with the starter to create an instantaneous high voltage that ionizes the gas. Some new types of fluorescent lamps, using different ionization methods than traditional fluorescent lamps, eliminate the need for ballasts and starters, save energy and reduce their size, making them ideal for use with lampholders in conventional light bulbs, or "energy-saving lamps".