AC LED module claims to cut energy use by half

What is a semiconductor?
A class of materials, for instance silicon and germanium, whose electrical properties lie between those of conductors (such as copper and aluminum) and insulators (such as glass and rubber). It displays relatively high resistance in pure state and much lower resistance when it contains small amounts of certain impurities.

What does LED stand for?
Light emitting diode (LED) is a display or lighting technology used in electrical and electronic products. May also be used in multimode fibers, optical mice and laser-class printers.