A light-emitting diode (LED) is a two-lead semiconductor light source.

It is a p–n junction diode that emits light when activated.

When a suitable current is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.

This effect is called electroluminescence, and the colour of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor.

LEDs are typically small (less than 1 mm2) and integrated optical components may be used to shape the radiation pattern.

Ireland (Ulster-Scots) is an island in the North Atlantic.

It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel.

Ireland is the third-largest island in Europe.

Advertising is an audio or visual form of marketing communication that employs an openly sponsored, non-personal message to promote or sell a product, service or idea.

Sponsors of advertising are typically businesses wishing to promote their products or services.

Advertising is differentiated from public relations in that an advertiser pays for and has control over the message.

It differs from personal selling in that the message is non-personal, i.e., not directed to a particular individual.

In marketing, a product is anything that can be offered to a market that might satisfy a want or need.

In retailing, products are called merchandise.

In manufacturing, products are bought as raw materials and sold as finished goods.

A service is another common product type.

In ordinary usage, a price is the quantity of payment or compensation given by one party to another in return for one unit of goods or services.