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A light-emitting-diode (LED) is a semiconductor diode that emits light when an electric current is applied in the forward direction of the device, as in the simple LED circuit. The effect is a form of electroluminescence where incoherent and narrow-spectrum light is emitted from the p-n junction.

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LED backlighting is most commonly used in small, inexpensive LCD panels. The light is usually colored, although white LED backlighting is becoming more common. ELP backlighting is often used for larger displays or when even backlighting is important; it can also be either colored or white. An ELP must be driven by relatively high voltage AC power, which is provided by an inverter circuit. CCFL backlights are used on large displays like computer monitors, and are usually white in color. These also require the use of an inverter and diffuser. Incandescent backlighting can be used when very high brightness is desired, but a drawback is the limited life of incandescent bulbs, and the amount of heat generated, which often means that the bulb needs to be mounted away from the display.

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Smart meter often refers to an electrical meter, but it can increasingly also mean a device measuring natural gas or water consumption.
Similar meters, usually referred to as interval or time-of-use meters, have existed for years, but Smart Meters usually involve a different technology mix, such as real-time or near real-time sensors, power outage notification, and power quality monitoring. These additional features are more than simple automated meter reading (AMR). They are similar in many respects to advanced metering infrastructure (AMI) meters. Smart meters are also believed to be a less costly alternative to traditional interval or time-of-use meters and are intended to be used on a wide scale with all customer classes, including residential customers. Interval and time-of-use meters are more of a legacy technology that historically have been installed to measure commercial and industrial customers, but typically provide no AMR functionality. Smart meters may be part of a smart grid, but alone do not constitute a smart grid. The installed base of smart meters in Europe at the end of 2008 was about 39 million units according to analyst firm Berg Insight[8].

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A smart grid delivers electricity from suppliers to consumers using two-way digital technology to control appliances at consumers' homes to save energy, reduce cost and increase reliability and transparency. It overlays the electricity distribution grid with an information and net metering system.
Such a modernized electricity network is being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues. Smart meters may be part of a smart grid, but alone do not constitute a smart grid.
A smart grid includes an intelligent monitoring system that keeps track of all electricity flowing in the system. It also incorporates the use of superconductive transmission lines for less power loss, as well as the capability of integrating renewable electricity such as solar and wind. When power is least expensive the user can allow the smart grid to turn on selected home appliances such as washing machines or factory processes that can run at arbitrary hours. At peak times it could turn off selected appliances to reduce demand.
Similar proposals include smart electric grid, smart power grid, intelligent grid (or intelligrid), FutureGrid, and the more modern intergrid and intragrid.