The old and faithful incandescent light bulbs are being forced out of automotive lighting, to be replaced by LED lights. LED is short for Light Emitting Diodes. This is a form of transistor, doped with a substrate that emits light when current is applied. The LEDs have a number of advantages over incandescent lighting that are very attractive for automotive use:

They last for the life of the vehicle (does not apply to headlight LEDs yet)
They light up much quicker than incandescent bulbs
They can be made to emit different colors
They give more light per supplied watt than incandescent light bulbs

There is now LED lighting technology available for every conventional automotive lighting purpose. The LEDs are also creating new light features for automotive purposes, as the LEDs can be installed in ways and in locations that are impossible with incandescent and fluorescent lighting.