What is a PCB
Have you ever opened up your computer or phone? The PCB or printed circuit board is the flat, typically green, piece that holds all the chips and/or electrical components. Below the green solder mask/overlay, are wires/traces on the board. They connect the components, creating circuits.
A PCB that has yet to have any electrical components soldered onto it, is called a “bare board”, or more properly, a “printed circuit board”. There are however copper traces called "wiring" that have been created by printing, plating, and etching processes.
To produce a PCB you need to take the functional diagram or schematic and transform it into a piece of artwork that makes a pattern for components, holes, and circuits/wires. The PCB designer is the engineer who creates the schematic. It is similar to the plates used in printing, although technically quite different.
PCB’s range in size, and are used in a multitude of products way too extensive to list, but here are a few: cell phones, autos, computers, TV’s, flash drives, thermostats, vehicles, weapons, and video game consoles. If it’s electronic, a PCB is probably the board holding the brains behind it.