Essential Parts of a Printed Circuit Board
The most obvious part is the circuit board itself. It is plastic, reinforced with glass. The next most obvious part is the lines and pads that are connected together. They are made of copper and are called "traces". They carry on electricity, allowing electricity to pass through the board. They are similar to wires, but are finer and used to deliver electricity to terminals.
A series of components can be incorporated into the PCB. No components, PCB is just an electrical conductor, no function. Common components include:
Diodes: allows current to pass in one direction only, blocking the other.
Inductor: These coils store charge in a magnetic field.
Light emitting diodes (LEDs). These light up when current flows is applied. They only allow current to flow in one direction.
Resistors: These control the electric current as it passes through. The level of resistance provided varies based on the needs of the engineer. They are made in different color codes to show the level of resistance.
Transistors: These are a form of switch that performs changes function based on the voltage passing through.
Vias: small holes in the board that allow a signal to be passed from one side to the other.