Any modern electrical device requires a huge number of connections to join together all the small components needed for it to work effectively. At one time these connections were made by wires that had to be soldered together. The wires have now been replaced by the printed circuit, which is effectively a picture of the wiring that works just as well.
A thin sheet of copper is attached to a special board made of insulating material. An image of the electrical circuit is then printed photographically onto the copper sheet. Chemicals are used to dissolve most of the copper, leaving behind a thin film of metal bands, to which all the necessary components can be attached. This process can be carried out automatically.
Picture credit: google