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Instead of a glowing filament, CFLs contain argon and mercury vapor housed within a spiral-shaped tube. They also have an integrated ballast, which produces an electric current to pass through the vaporous mixture, exciting the gas molecules. In older CFLs, it took several seconds for the ballast to produce enough electricity to ramp up the excitation. Newer CFLs have more efficient ballasts and require a shorter warm-up. Either way, when the gas gets excited, it produces ultraviolet light. The ultraviolet light, in turn, stimulates a fluorescent coating painted on the inside of the tube. As this coating absorbs energy, it emits visible light.

A fluorescent lamp or a fluorescent tube is a low pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light instead of having filament. An electric current in the gas excites mercury vapor which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the bulb to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than incandescent lamps. The luminous efficacy of a fluorescent light bulb can exceed 100 lumens per watt, several times the efficacy of an incandescent bulb with comparable light output.

Incandescent create light by use of a filament. When power is applied, the filament glows, generating heat, in turn, producing light. LEDs are the opposite. LEDs create light though a "cold process", when power is applied to semiconductors (usually gallium, arsenic and phosphorus) they're stimulated by the movement of electrons; thus creating photons, the light that is visibly seen by humans.