A transistor is a semiconductor component used to control current. It can work like an electronic switch, turning a circuit on and off, or like an amplifier, making a small signal stronger.
Why transistors are important
Modern electronics depend heavily on transistors. They are found in processors, memory chips, power controls, audio amplifiers, sensors, and almost every digital device.
Transistor as a switch
A small control signal can allow a transistor to control a larger current. That makes it useful for turning on motors, LEDs, relays, and other loads from a microcontroller.
The transistor is one of the main building blocks behind modern computing and electronics.