Printed circuit boards (PCB) are commonly made from fiberglass and epoxy as non-conductive substrate, with copper tracks that are used to connect the components of the electronic circuit to be assembled in the board.
Most of the pcb available are coated with a protective layer called soldermask, that allows for easy soldering and protects against bridging and short circuits.
There are many varieties of printed circuit boards, each with its own use in the electronics industry. Some of the most common types are multilayer boards.
Multilayer boards include additional copper and insulating layers, often to increase component density by using the additional copper planes as power and ground, eliminating the need for those tracks.
Other special boards include metal core boards used to dissipate heat better, flexible pcbs for slim or moving parts, and smd boards, that are fabricated in the same way, except that no drilling is required and pads have a different layout.