 Prototypes which are subject to modification are often not made on PCBs, using instead breadboard construction.Historically this could be literally a breadboard, a wooden board with components attached to it and joined up with wire.More recently the term is applied to a board of thin insulating material with holes at standard 0.1-inch pitch; components are pushed through the holes to anchor them, and point-to-point wired on the other side of the board.