In the electronic devices we use in our daily life, such as remote controls, mobile phones, refrigerators, TVs, air conditioners, computers, etc., there is an important part called "circuit board", but its formal full name should be "printed circuit board", because the formation of its electronic circuits is really similar to the early printing of books, so its English abbreviation is "PCB (Printed Circuit Board)", and some people abbreviate it as "PWB (Printed Wire Board)".
In short, PCB is like the base of electronic equipment, responsible for connecting all electronic components in the same network so that they can work together.
You can think of PCB as the chassis of a car, and all the parts of the car will be installed on it, so that they can work together. But I personally think that PCB is more like a piece of town land with roads built in an urban plan, waiting for other government buildings to move in at fixed locations. And the well-developed town is a PCBA (Printed Circuit Board Assembly), which we usually call "assembled circuit board" or "assembly board".
The main body of the PCB is a hard board with a thickness of about 1.0mm~1.6mm. Depending on the design requirements, the thickness of the PCB will be thinner or thicker, and some will be specially designed to be flexible and bendable (FPCB). For some more special needs, the hard board and the soft board will be combined together to form a rigid-flex board.
On the board, there will be one or more layers of conductive metal, usually copper foil. This layer of metal is cleverly designed into a network (electronic circuit), just like the streets in a town, allowing different components in electronic equipment to communicate and collaborate.
These components can be passive components such as resistors, capacitors, inductors, or active transistors, integrated circuits (ICs), etc., and they all have their own functions. When these components are connected together through the metal network on the PCB, a complete circuit is formed, just like the connection and connection of building organs in various locations in the city. After power is supplied, it will start to operate according to the design.
