A printed circuit board, or PCB, is the board that holds electronic components and connects them using copper paths called traces. It replaces loose wiring with a planned, compact layout.
What is on a PCB?
A PCB may hold resistors, capacitors, chips, connectors, sensors, switches, LEDs, and power components. The board can have one layer or several layers depending on complexity.
PCB versus breadboard
A breadboard is used for temporary experiments without soldering. A PCB is usually the more permanent form used in a finished product.
When you open most electronic devices, the green or dark board inside is usually a PCB.