Surface Mount Device. The name given to components which are soldered directly to the surface of the PCB (printed circuit board). SMD devices are very common no

Surface Mount Device. The name given to components which are soldered directly to the surface of the PCB (printed circuit board). SMD devices are very common now and replace older components which had legs (or leads) which had to pass through holes in the circuit board, also known as "leaded components" or through-hole.