Transistors are tiny semiconductor devices that act as switches or amplifiers by controlling the flow of current. Modern processors, memory chips, and most digital logic are built from billions of them, so they are the basic building blocks of hardware behavior. Their reliable switching depends on material properties, voltage thresholds, timing, and environmental conditions.
In cyber security, transistors matter because attacks often exploit the hardware they form. Fault injection, voltage or clock glitches, laser or electromagnetic manipulation, and some side-channel techniques all try to disturb transistor-level operation. Defenders care about them because changes in fabrication, aging, heat, or even light-sensitive materials can affect how a circuit behaves. That is why hardware security includes careful validation, tamper resistance, and testing for unexpected state changes, not just software controls.