This is a pretty good article explaining LED lighting and the science behind it…
It seems like they’re already everywhere – if you look down at your keyboard, one is providing the little green indicator for your Num Lock key, while another may be frantically blinking to inform you of your waiting voice mail. On your next drive, chances are you will stop at a stoplight lit purely by LED’s and perhaps may notice a blinker made up of small, bright lights instead of one bulb. LED’s certainly are everywhere, faithfully providing indications of all kinds. But, with a few exceptions, the primary purpose of an LED is to indicate rather than illuminate, despite the fact that LED’s do nothing useful besides produce light. A few new developments, however, may bring solid-state lighting into our homes very soon.
