What is the primary function of a transistor?

The primary function of a transistor is to act as an electronic switch. This capability allows transistors to control the flow of electrical current within a circuit. By applying a small input voltage to the transistor, a larger current can be allowed to flow or be cut off, enabling the device to switch between an 'on' and 'off' state. This on/off behavior is fundamental in digital electronics and is the basis for binary computing.

Transistors can also amplify signals, which is a secondary function, but their most critical role is as a switch in countless electronic applications, including logic circuits, amplifiers, and various types of electronic devices. Other functions mentioned, such as storing electrical energy, amplifying sound waves, or generating power, do not accurately capture the primary operational role that transistors perform.