SMD stands for Surface Mounted Device, a special category of LEDs, which have tiny metallic contacts that can be directly soldered to circuit boards. Mass produced electronic circuit boards need to be manufactured in a highly mechanized fashion in order to save on manufacturing costs. However, traditional leaded electronic components do not lend themselves to such an approach. In industry, SMDs have largely replaced the through-hole-technology (THT) construction method of fitting components with wire leads into holes in the circuit board. The most common example of an SMD is the smart phone. It has components that need to be packed very tightly in a very slim case, so it is not feasible use THT. Surface mounted technologies can be smaller than THT because they have smaller leads, or no leads at all, making them easier to shrink down.