n a strict sense, transistors generally refer to all single components based on semiconductor materials, including diodes (two-terminal), triodes, field-effect tubes, and thyristors (the last three are three-terminal) made of various semiconductor materials. Transistors sometimes multidigit transistor. Three-terminal transistors fall into two main categories: bipolar transistors (BJT) and field-effect transistors (FETs). A transistor has three poles (terminals); The three poles (terminals) of a bipolar transistor are respectively the Emitter, Base and Collector composed of N-type and P-type semiconductors. The three poles (terminals) of a field-effect transistor are the Source, the Gate and the Drain.

Because the transistor has three electrodes, it also has three ways of using, respectively, emitter grounding (also known as common emitter amplification, CE configuration), base grounding (also known as common base amplification, CB configuration) and collector grounding (also known as common set amplification, CC configuration, emitter with coupler).

Because of their fast response speed and high accuracy, transistors can be used for a wide variety of digital and analog functions, including amplification, switching, voltage regulation, signal modulation, and oscillators. Transistors can be packaged individually or in a very small area that can accommodate one hundred million or more transistors as part of an integrated circuit.