Printed Circuit Boards, or PCB's, are the plates on which the circuit is placed. Although technically a PCB is not needed, as you could create all connections with just wire, they can be found everywhere. The first PCB's were added to consumer products in the 1950's. Their handdrawn traces are recognisable by their curvynes, and the PCB's are either single layer(one side) or double layer (front & back). Contemporary PCB's are digitally designed and usually multi-layer, allowing for a small footprint, but making it very difficult to repair.
Have you spotted “The Blob” yet? This is every circuit benders worst nightmare. The blob is meant to protect certain bare parts of a PCB, but is also known as a type of reverse engineering protection.
