LED stands for Light-emitting Diode. It is a device that emits visible light when an electrical current is passed through it. LED lighting come in various different colours and strengths, with colours ranging from white to red to blue-violet, there are also mood sets like cool white and warm white to name a few.
Why use LED's instead of normal down lights (incandescent):
Less Power: LED's require a lot less power so not only save on electricity but also help the environment,
Higher efficiency: Most of the power supplied to an LED lighting is converted into light but with an incandescent light 5% is light and 95% is heat.
Life expectancy: If properly installed LED lighting can last for decades and most manufactures give a 7 to 10 year warranty on their products.
So although the LED light fitting is far more expensive than a conventional incandescent lamp the longevity of the LED far exceeds it so in the long run you pay less and help with the environment.