Ballasts – Ballasts are electronic devices that fluorescent lights use to function. Without ballasts, fluorescent lights would easily fail or would never even light at all. The ballast keeps the bulb’s current balanced and allows the light to function. Magnetic ballasts are based on a simple magnetic transformer made of a steel core and copper wire wrappings to produce an electromagnetic current. The ballast also uses capacitors to limit and control the current as needed. Electronic ballasts use electronic circuits to convert the AC (and sometimes DC) line, to the voltages a fluorescent tube needs to light. Electronic ballasts are much more energy efficient than magnetic ballasts
Compact Fluorescent Lamp (CFL) – A family of single-ended fluorescent-discharge light sources with small-diameter [16-millimeter (5/8-inch) or less] tubes.
Efficacy – Efficacy is an industry term for the amount of light produced per watt of electricity (comparable to efficiency). It is the rate at which a light bulb is able to convert electrical power (watts) into light (lumens), expressed in terms of lumens per watt (LPW). For example, a 100 watt lamp producing 1750 lumens gives 17.5 lumens per watt.
Fluorescent Lighting – A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light much more efficiently than incandescent lamps. The luminous efficacy of a compact fluorescent light bulb is about 60 lumens per watt, four times the efficacy of a typical incandescent bulb. For conventional tube fluorescent lamps the fixture is more costly because it requires an ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost. (From wikipedia)
LED – (Light Emitting Diode) LED lighting offers long service light and hight energy efficiency than regular lighting.
LED Retrofitting – replacing conventional fluorescent, neon or other lighting with more efficient LED lighting
Lumen – is a measure of the total visible light output of a light source.