A variety of LED lights, from different suppliers
LED lights are quite different from ordinary mains or low-voltage lighting. For a start, they don't have “bulb”, using instead a “Light Emitting Diode” This has several advantages (and disadvantages) when compared to a low 12volt halogen bulb, which is the mainstay of garden lighting:
One diode does not emit much light, so most units comprise of a cluster of diodes, set in one lamp (you can see in the picture that the large light unit has a lot of diodes in it). LEDs use minute quantities of low voltage electricity, so are cheap to run. diodes don't blow, in the way that bulbs do, so will have a life of 30 - 50,000 hours, or more. Many light units are therefore sealed for life. They do not get hot, unlike halogen, which can burn and they come in a range of colours, which you cannot see until the unit is switched on.
A small LED installed in a deck
Even a large LED will not emit as much light as a halogen bulb, however. If you want to illuminate an area, LEDs are not the best choice. The light spectrum is different also, LEDs give off a blue-white light, which can feel cold compared to the warmer yellow-white light of halogen.
The ideal way to use LEDs therefore, is as marker lights set into paving, steps, decks and drives. That way they highlight and define the area and edges, no one gets hurt if they are walked upon with bare feet and they can be installed in places where they are hard to access, knowing that there are no bulbs to replace, requiring major excavation or deconstruction!
Samples of coloured LED lights
LEDs are a “new technology” when it comes to lighting. Cheaper than Fibre Optics but with as much potential, I have no doubt there will come a day when use of these lights will become the norm, with halogens consigned to history. We're not there just yet, though.