Stands for "Printed Circuit Board." A PCB is a thin board made of fiberglass, composite epoxy, or other laminate material. Conductive pathways are etched or "printed" onto board, connecting different components on the PCB, such as transistors, resistors, and integrated circuits.
PCBs are used in both desktop and laptop computers. They serve as the foundation for many internal computer components such as video cards and controller cards, network interface cards, and expension cards. These components all connect to the motherboard,which is also a printed circuit board.
While PCBs are often associated with computers, they are used in many other electronic devices besides PCs. Most TVs, radios, digital cameras, cellphones, and tablets include one or more printed circuit boards. While the PCBs found in mobile devices look similar to those found in desktop computers and large electronics, they are typically thinner and contain finer circuitry.
The two diagrams above show the track side of a PCB (normally the underneath side) and the component side (normally the top side) of the same circuit. The relay and integrated circuit are ready to be placed in position and soldered.