A technology for mounting
electronical components onto
printed circuit boards (PCBs).
Holes are drilled into the printed circuit boards. Then the electronical components' wires are stuck through these holes and soldered thight on the other side of the board.
A simple and effective way of mounting components if you plan to do it manually, but in contrast to the
SMD technology, it's harder to build machines that can do it, therefore it's not useful for
mass production. Nowadays it's hard to find printed circuit boards with through-hole technology, because SMD has nearly completely replaced it.