What is a transistor?

A transistor is a semiconductor device that can amplify or switch electronic signals and electrical power. It generally has three terminals. By applying a voltage or current to one pair of terminals, you control the current between the other two.

In more detail: the invention of the first practical transistor at Bell Labs in 1947 ushered in the era of modern electronics. Types include the bipolar junction transistor (BJT) with emitter-base-collector terminals and the field-effect transistor (FET) with gate-source-drain terminals.

Uses: in audio amplifiers, radio frequency circuits, digital logic (where transistors act as switches), integrated circuits, and power electronics. The transistor’s ability to control large currents with small inputs makes it foundational. when you hear transistor think of a tiny switch/amplifier inside virtually all modern electronic devices.