Array: An order or arrangement of LEDs.

Cold cathode fluorescent lamp (CCFL): A type of fluorescent lamp that does not employ a cathode heater to produce light. Also known as a cold cathode fluorescent tube (CCFT), a CCFL can be used in backlit screen applications. Examples of CCFLs including neon lamps and nixie tubes.

Color gamut: The complete subset of colors that can be accurately represented in a given circumstance.

Color rendering index (CRI): Measure of the degree of color shift an object undergoes when illuminated by a light source as compared to a reference source of the same color temperature. CRI is expressed on a scale of 0-100, with a higher value representing less color distortion, or a more “accurate” color. Natural daylight is rated 100.

Color spectrum: The distribution of colors produced when light is dispersed by a prism.

Compact fluorescent lighting (CFL): A type of fluorescent lamp. Many CFLs are designed to replace incandescent lighting and can fit in existing light fixtures formerly used for incandescent bulbs. Compared to general service incandescent lamps giving the same amount of visible light, CFLs consume less power and last longer.

Compound semiconductor: A semiconductor that is composed of two or more elements.

Chip: Usually made up of silicon, a chip is a minute semiconductor which contains hundreds and thousands of electronic components. It is also known as an integrated circuit.

Die: A semiconductor that has not yet been packaged. Also known as a “chip”.

Epitaxy: The process of depositing a thin layer of single crystal material over a single crystal substrate. In semiconductors, the deposited film is often the same material as the substrate.

Flux: The sum of all lumens emitted by a light source.

Incandescent lighting: Light produced when a filament is heated to incandescence using an electric current (e.g., light bulb). Incandescent lighting is very inefficient—turning much of its energy into heat rather than light—and is gradually being replaced in many applications by LEDs and other devices.

InGaN (indium gallium nitride): A semiconductor material composed of a mix of gallium nitride and indium nitride, which is used to manufacture blue- and green-colored light-emitting diodes (LEDs).

LED: Also known as a light-emitting diode, an LED is a solid-state semiconductor that emits light. LEDs are used in a variety of display and lighting applications, and consume less power than incandescent bulbs.

Light engine: A subsystem used to generate light, which typically includes a lamp module, optics and projection lens.

Light source: Any device serving as a source of illumination

Lumen: A unit of measurement that expresses the total quantity of light given off by a source, regardless of direction. One lumen is equal to the amount of light that one candle emits over one square foot of surface that is exactly one foot away from the flame.

Nit: A unit of luminance used for estimating brightness.

Packaged LED: An LED package has an optical lens, bonding wire (to bond the package to the printed circuit board), electrodes, and resin to encapsulate the LED for protection.

RGB: Acronym for red, green and blue, which are the three primary colors of light. Also refers to the color model for displays and monitors, where combinations of illuminated red, green and blue pixels are used to create a wide variety of colors.

Solid-state lighting (SSL): A form of lighting that makes use of light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as sources of illumination as opposed to electrical filaments or gas.

Thermal management: Ability to control the temperature (heat) of the device junctions in packaged LEDs, often through the use of heat sinks. Junction heat can negatively impact the performance of LED lighting, including output, color and lifetime.

Thermal resistance: The measure of a material’s resistance to heat flow. In packaged LEDs, thermal resistance is used as an indirect method of determining LED junction temperature.

Volt: A unit of measurement for electric potential and electromotive force.

Watt: A unit of measurement for power equal to one joule of energy per second.