# LED Lighting Glossary

> Quick definitions for the most common LED lighting terms and technologies.

**Source:** <https://ledlightinginfo.com/glossary>

## Terms
- [0-10V Dimming](https://ledlightinginfo.com/glossary/0-10v-dimming.md): A commercial/architectural dimming standard that uses a separate low-voltage signal wire (0-10V) to control brightness. Common in offices, warehouses, and professional installations.
- [A19 Bulb](https://ledlightinginfo.com/glossary/a19-bulb.md): The standard household light bulb shape — a pear-shaped bulb 2.375 inches in diameter, used in most lamps and fixtures.
- [A21 Bulb](https://ledlightinginfo.com/glossary/a21-bulb.md): A slightly larger version of the standard A19 bulb — 2.625 inches in diameter. Used for higher-wattage LED bulbs that need more space for heat dissipation.
- [Accent Lighting](https://ledlightinginfo.com/glossary/accent-lighting.md): Decorative, directional light used to highlight artwork, architectural features, or plants. The third layer of lighting design — adds drama and visual interest.
- [Addressable LEDs](https://ledlightinginfo.com/glossary/addressable-leds.md): LED strips where each LED (or small group) can be controlled independently for color and brightness — enabling rainbow effects, animations, and music sync.
- [Ambient Lighting](https://ledlightinginfo.com/glossary/ambient-lighting.md): The primary, overall illumination in a room — the base layer that provides uniform light for general visibility. Usually from ceiling fixtures, recessed lights, or large floor lamps.
- [B22 Base](https://ledlightinginfo.com/glossary/b22-base.md): A bayonet cap base with a 22mm diameter, standard in the UK, Australia, and parts of Asia. Push-and-twist to lock into the socket.
- [BR30 Bulb](https://ledlightinginfo.com/glossary/br30-bulb.md): A bulge reflector shape 3.75 inches in diameter, designed for recessed can fixtures. Produces a wide, even flood of light directed downward.
- [Ballast](https://ledlightinginfo.com/glossary/ballast.md): A device that regulates current for fluorescent and HID lamps. When upgrading to LED tubes, you may need to bypass the ballast depending on the tube type.
- [Beam Angle](https://ledlightinginfo.com/glossary/beam-angle.md): The angle at which light spreads from a bulb. Narrow angles (15-30°) create spotlights; wide angles (60-120°) create flood light.
- [Binning](https://ledlightinginfo.com/glossary/binning.md): The manufacturer process of sorting LED chips by color temperature, brightness, and voltage into consistent groups (bins). Tighter binning means more consistent light across multiple bulbs.
- [COB (Chip on Board)](https://ledlightinginfo.com/glossary/cob.md): A dense array of LED chips bonded directly to a substrate, producing a seamless, dot-free light output. Used in high-end strip lights and downlights.
- [CRI (Color Rendering Index)](https://ledlightinginfo.com/glossary/cri.md): A 0-100 scale measuring how accurately a light source reveals true colors compared to sunlight. 90+ is considered excellent.
- [Chandelier](https://ledlightinginfo.com/glossary/chandelier.md): A decorative branched ceiling fixture with multiple light sources. Ranges from traditional crystal designs to modern minimalist styles. Usually the visual focal point of a room.
- [Clear Bulb](https://ledlightinginfo.com/glossary/clear-bulb.md): A bulb with transparent glass that shows the LED filament or chips inside. Produces sharper, more decorative light with visible sparkle.
- [Color Temperature](https://ledlightinginfo.com/glossary/color-temperature.md): A measure of light appearance in Kelvin (K) — lower values are warm/yellow, higher values are cool/blue-white. Ranges from candlelight at 2200K to daylight at 6500K.
- [Cut Marks](https://ledlightinginfo.com/glossary/cut-marks.md): Designated points on an LED strip where you can safely cut to shorten it. Marked with a scissor icon or copper pads — cutting between marks will damage the circuit.
- [DRL (Daytime Running Light)](https://ledlightinginfo.com/glossary/drl.md): Always-on front lights that make vehicles more visible during the day. Usually low-intensity LED strips or dedicated bulbs that activate automatically with the engine.
- [Dark Sky Compliant](https://ledlightinginfo.com/glossary/dark-sky-compliant.md): Fixtures designed to minimize light pollution by directing light downward and using warm color temperatures (3000K or below). Certified by the International Dark-Sky Association.
- [Dimming Range](https://ledlightinginfo.com/glossary/dimming-range.md): The brightness span a dimmer can achieve — typically expressed as a percentage (e.g., 5%-100%). A wider range means dimming to a lower level without flickering or shutting off.
- [Dipped Beam / Low Beam](https://ledlightinginfo.com/glossary/dipped-beam.md): The standard headlight setting for everyday driving — angled downward and to the side to illuminate the road without blinding oncoming traffic.
- [E12 Base](https://ledlightinginfo.com/glossary/e12-base.md): A smaller 12mm Edison screw base used in decorative fixtures like chandeliers, wall sconces, and night lights.
- [E26 / E27 Base](https://ledlightinginfo.com/glossary/e26-base.md): The standard Edison screw base used in most household lamps and fixtures. E26 (26mm) is the North American version, E27 (27mm) is the European equivalent.
- [Efficacy](https://ledlightinginfo.com/glossary/efficacy.md): The efficiency of a light source measured in lumens per watt (lm/W). Higher efficacy means more light for less electricity.
- [Flicker](https://ledlightinginfo.com/glossary/flicker.md): Rapid, repeated changes in light output. Can be visible (strobe effect) or invisible but still cause headaches. Usually caused by incompatible dimmers or poor LED drivers.
- [Floor Lamp](https://ledlightinginfo.com/glossary/floor-lamp.md): A freestanding light fixture that sits on the floor, providing ambient or task lighting without ceiling installation. Types include torchiere (uplight), arc, tripod, and reading lamps.
- [Fog Lights](https://ledlightinginfo.com/glossary/fog-lights.md): Low-mounted, wide-beam lights designed to illuminate the road surface in fog, rain, or snow. Positioned below headlights to avoid reflecting off water droplets back at the driver.
- [Foot Candle](https://ledlightinginfo.com/glossary/foot-candle.md): A measure of illuminance in imperial units — one lumen per square foot. Commonly used in US building codes and lighting design.
- [Frosted Bulb](https://ledlightinginfo.com/glossary/frosted-bulb.md): A bulb with a diffused white coating that softens light output, hides internal LED chips, and reduces glare.
- [GFCI Protection](https://ledlightinginfo.com/glossary/gfci-protection.md): A safety device that instantly cuts power when it detects current leaking to ground — preventing electrocution. Required by code for outdoor, bathroom, kitchen, and pool/spa lighting circuits.
- [GU10 Base](https://ledlightinginfo.com/glossary/gu10-base.md): A twist-and-lock spotlight base with two pins spaced 10mm apart. Runs on mains voltage (120V/240V) — no transformer needed.
- [GU5.3 Base](https://ledlightinginfo.com/glossary/gu5-3-base.md): A bi-pin base with two pins spaced 5.3mm apart, used for low-voltage (12V) MR16 spotlight bulbs. Requires a transformer.
- [Geofencing](https://ledlightinginfo.com/glossary/geofencing.md): A location-based automation trigger that activates lighting actions when your phone enters or leaves a defined area — like turning on porch lights when you arrive home.
- [H1 Bulb](https://ledlightinginfo.com/glossary/h1-bulb.md): A compact single-filament halogen bulb used in headlights and fog lights. Smaller than H7 with a different connector — common in older European and Japanese vehicles.
- [H4 Bulb](https://ledlightinginfo.com/glossary/h4-bulb.md): A dual-filament headlight bulb that handles both low beam and high beam in a single unit. Common in motorcycles, older cars, and many Asian and European vehicles.
- [H7 Bulb](https://ledlightinginfo.com/glossary/h7-bulb.md): A single-filament halogen headlight bulb commonly used for low beam or high beam in European vehicles. One of the most popular bulbs for LED headlight upgrades.
- [HID Lights (Xenon)](https://ledlightinginfo.com/glossary/hid-lights.md): High Intensity Discharge lights that create light by arcing electricity through xenon gas. Brighter and whiter than halogen, but being replaced by LEDs in modern vehicles.
- [Heat Sink](https://ledlightinginfo.com/glossary/heat-sink.md): A component (usually aluminum) that absorbs and dissipates heat from LED chips. Critical for lifespan — LEDs don't burn out, they overheat.
- [High Beam](https://ledlightinginfo.com/glossary/high-beam.md): The brightest headlight setting with a wider, further-reaching pattern. Used on unlit roads with no oncoming traffic — must be dipped when other vehicles approach.
- [IC Rated](https://ledlightinginfo.com/glossary/ic-rated.md): A safety rating for recessed light fixtures that are approved for direct contact with ceiling insulation. Non-IC fixtures require clearance from insulation to prevent fire risk.
- [IP Rating](https://ledlightinginfo.com/glossary/ip-rating.md): Ingress Protection rating — a two-digit code indicating resistance to dust (first digit, 0-6) and water (second digit, 0-9). Higher numbers mean better protection.
- [Integrated LED](https://ledlightinginfo.com/glossary/integrated-led.md): A fixture with LED chips built directly into the housing — no replaceable bulb. Generally more efficient and slimmer, but the entire fixture must be replaced when LEDs fail.
- [LED Channel](https://ledlightinginfo.com/glossary/led-channel.md): An aluminum housing that mounts LED strips for a professional finish. Includes a diffuser cover that eliminates visible LED dots and improves heat dissipation.
- [LED Density](https://ledlightinginfo.com/glossary/led-density.md): The number of LED chips per meter on a strip light. Higher density produces smoother, more even light with fewer visible dots. Common values: 30, 60, 120, or 144 LEDs/m.
- [LED Driver](https://ledlightinginfo.com/glossary/led-driver.md): A power supply that regulates current to LEDs, preventing flickering and enabling dimming. Every LED has one — either built into the bulb or as an external unit.
- [LED Lifespan (L70)](https://ledlightinginfo.com/glossary/led-lifespan.md): The number of hours until an LED degrades to 70% of its original brightness (L70). Typical LED bulbs are rated 25,000-50,000 hours.
- [Leading Edge Dimmer](https://ledlightinginfo.com/glossary/leading-edge-dimmer.md): A dimmer type that cuts the leading (front) edge of each AC wave. Originally designed for incandescent and halogen — can cause buzzing and flicker with LEDs.
- [Low Voltage Lighting](https://ledlightinginfo.com/glossary/low-voltage-lighting.md): Lighting systems that operate on 12V or 24V instead of mains voltage (120V/240V). Common in landscape lighting and LED strips — safer to install and requires a transformer.
- [Lumens](https://ledlightinginfo.com/glossary/lumens.md): The unit measuring total visible light output. Unlike watts, lumens tell you how bright a bulb actually is.
- [Lux](https://ledlightinginfo.com/glossary/lux.md): A measure of illuminance — how many lumens hit one square meter of surface. Used to specify lighting levels for rooms and workspaces.
- [MR16 Bulb](https://ledlightinginfo.com/glossary/mr16-bulb.md): A compact multifaceted reflector bulb 2 inches in diameter, commonly used in track lighting, display cases, and landscape fixtures. Usually runs on 12V.
- [Matter](https://ledlightinginfo.com/glossary/matter.md): A unified smart home standard backed by Apple, Google, Amazon, and Samsung. Devices certified for Matter work across all major ecosystems — ending the 'which app?' problem.
- [Minimum Load](https://ledlightinginfo.com/glossary/minimum-load.md): The lowest wattage a dimmer switch needs to function properly. Many older dimmers require 40-60W minimum — a single 9W LED bulb won't meet that threshold, causing flickering or failure to dim.
- [Neutral Wire](https://ledlightinginfo.com/glossary/neutral-wire.md): The return path for electrical current in a circuit (usually the white wire in US wiring). Many smart switches require a neutral wire — older homes often don't have one in the switch box.
- [PAR38 Bulb](https://ledlightinginfo.com/glossary/par38-bulb.md): A parabolic aluminized reflector bulb 4.75 inches in diameter. Produces a focused, controlled beam — commonly used for outdoor floods and track lighting.
- [PWM Dimming](https://ledlightinginfo.com/glossary/pwm-dimming.md): A dimming method that rapidly switches LEDs on and off thousands of times per second. The ratio of on-time to off-time controls perceived brightness.
- [Pendant Light](https://ledlightinginfo.com/glossary/pendant-light.md): A light fixture that hangs from the ceiling by a cord, chain, or rod. Used for both ambient and task lighting — common over kitchen islands, dining tables, and entryways.
- [Phosphor](https://ledlightinginfo.com/glossary/phosphor.md): A yellow coating applied over a blue LED chip that converts part of the blue light into other wavelengths, creating white light. The phosphor blend determines color temperature and CRI.
- [Photocell / Dusk to Dawn Sensor](https://ledlightinginfo.com/glossary/dusk-to-dawn.md): A light-sensitive sensor that automatically turns lights on at dusk and off at dawn. Built into some fixtures or available as a standalone add-on for outdoor lighting.
- [Projector Housing](https://ledlightinginfo.com/glossary/projector-housing.md): A headlight type that uses a convex lens to focus and shape the light beam into a sharp, defined pattern. Handles LED and HID upgrades much better than reflector housings.
- [RGB & Color Mixing](https://ledlightinginfo.com/glossary/rgb-color-mixing.md): LED technology that combines red, green, and blue diodes to create millions of colors. Variants include RGBW (adds white), RGBWW (adds warm + cool white), and RGBIC (independently addressable segments).
- [Recessed Lighting](https://ledlightinginfo.com/glossary/recessed-lighting.md): Light fixtures installed flush into the ceiling, creating a clean, unobtrusive look. Also called can lights or downlights. Available as integrated LED or with replaceable bulbs.
- [Reflector Housing](https://ledlightinginfo.com/glossary/reflector-housing.md): A headlight type that uses a chrome-coated bowl to bounce light forward. Simpler and cheaper than projectors, but LED upgrades can cause scattered light and glare issues.
- [Remote Control](https://ledlightinginfo.com/glossary/remote-control.md): A handheld device for controlling lights without wall switches or apps. Common types include IR (line-of-sight), RF (through walls), and Bluetooth remotes.
- [SMD (Surface Mount Device)](https://ledlightinginfo.com/glossary/smd.md): A type of LED chip soldered directly onto a circuit board. Common in strip lights — the number (2835, 5050) indicates the chip dimensions in tenths of millimeters.
- [Smart Hub](https://ledlightinginfo.com/glossary/smart-hub.md): A central device that bridges smart home protocols (Zigbee, Z-Wave) to your home network. Required for some smart lights, optional for Wi-Fi bulbs.
- [Smart Lighting Scene](https://ledlightinginfo.com/glossary/scene.md): A saved lighting configuration that sets multiple lights to specific brightness, color, and temperature levels with a single command. Like a preset for your entire room.
- [T8 Tube](https://ledlightinginfo.com/glossary/t8-tube.md): A tubular lamp 1 inch (26mm) in diameter, the standard size for commercial fluorescent lighting. LED T8 tubes are direct replacements.
- [TRIAC Dimmer](https://ledlightinginfo.com/glossary/triac-dimmer.md): The most common phase-cut dimmer circuit, found in most residential dimmers. Works by chopping the AC waveform. Some TRIAC dimmers work with LEDs, many don't.
- [Task Lighting](https://ledlightinginfo.com/glossary/task-lighting.md): Focused, brighter light directed at a specific work area — like a desk lamp, under-cabinet kitchen light, or reading light. The second layer of good lighting design.
- [Thread](https://ledlightinginfo.com/glossary/thread.md): A modern IP-based mesh networking protocol for smart home devices. Low-power like Zigbee but uses internet protocol natively — a foundation for Matter.
- [Three-Way Switch](https://ledlightinginfo.com/glossary/three-way-switch.md): A wiring configuration that controls one light from two different switch locations — common for hallways, staircases, and rooms with multiple entrances.
- [Trailing Edge Dimmer](https://ledlightinginfo.com/glossary/trailing-edge-dimmer.md): A dimmer type that cuts the trailing end of each AC wave cycle. Smooth, quiet, and compatible with most LED bulbs — the recommended type for LED dimming.
- [Watt Equivalent](https://ledlightinginfo.com/glossary/watt-equivalent.md): A labeling convention that compares an LED bulb's brightness to the incandescent bulb it replaces — e.g., a '60W equivalent' LED produces the same ~800 lumens as a 60W incandescent while using only 9W.
- [Wattage](https://ledlightinginfo.com/glossary/wattage.md): A measure of electrical power consumption. For LEDs, lower wattage delivers the same brightness as higher-wattage incandescent bulbs.
- [Z-Wave](https://ledlightinginfo.com/glossary/z-wave.md): A smart home mesh protocol operating on sub-1GHz frequencies, avoiding Wi-Fi interference. Requires a hub and supports up to 232 devices per network.
- [Zigbee](https://ledlightinginfo.com/glossary/zigbee.md): A low-power wireless mesh protocol for smart home devices. Requires a hub but is more reliable and scalable than Wi-Fi — each device extends the network for others.