Electric luminaires generally consist of some or all of the following parts: sources; ballasts/power supplies; reflectors; shielding/diffusion components; and housings. These components are described in the following subsections.

Sources, Power Supplies & Ballasts
Electric light sources are lamps (such as fluorescent or metal halide) or solid-state devices (such as LEDs) with their respective lamp holders or sockets or mounting boards. Lamps are available in a wide array of types, sizes, wattages, distributions, colors, phosphor coatings, starting and operating characteristics, styles and thermal characteristics.
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Reflectors
Reflectors direct light where it is needed and may be used to shield the brightness of the lamp. Reflecting materials can be matte or specular, metallic or white, hammered or ridged, or a combination of these. It is the job of the reflector to capture some or most of the light emitted from the light source and effectively redirect it to more useful zones.
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Shielding & Diffusion Components
Shielding/diffusion components—lenses, wave guides, diffusers, baffles, louvers, and the like —are used to reduce light emitted toward the user’s eyes (glare), redirect light, concentrate light, widen the light pattern, or smooth out the light pattern.
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Housings
Housings contain shielding/diffusing components as well as electrical components, such as wiring connections, photosensors and other control devices. Advanced luminaires may feature smaller, lighter, easier-to-install, or easier-to-maintain housings.
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Controls
Some luminaires feature sensors and controllers installed as part of the luminaire for individual and grouped luminaire control.
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