TRANSISTORS
Modern computers use transistors to perform all computations.
A transistor is similar to an electronic switch, as it is a switch that can be opened or closed by applying electrical power to a control or base wire (B).
Most transistors have two electrodes, a collector (C), and an emitter (E).
They are separated by a gate electrode composed of a semiconducting material.
By changing the charge of the gate via the control wire, the conductivity of the semiconductor can be manipulated, allowing current to flow or be stopped.
Before transistors, computers used vacuum tubes and electromechanical switches as switches.
These were unreliable, bulky, fragile, and power-hungry.
Transistors could switch much faster and could be made much smaller than vacuum tubes or electromechanical switches.
This allowed for the creation of much smaller and inexpensive computers, such as this IBM 608.
Computers today use transistors that are smaller than 50 nanometers in size. For reference, a sheet of paper is around 100,000 nanometers thick.