A transistor is a basic electrical component that alters the flow of electrical current. Transistors are the building blocks of integrated circuits, such as computer processors, or CPUs. Modern CPUs contain millions of individual transistors that are microscopic in size.

Most transistors include three connection points, or terminals, which can connect to other transistors or electrical components. By modifying the current between the first and second terminals, the current between the second and third terminals is changed. This allows a transistor to act as a switch, which can turn a signal on or off. Since computers operate in binary, and a transistor's "on" or "off" state can represent a 1 or 0, transistors are suitable for performing mathematical calculations. A series of transistors may also be used as a logic gate when performing logical operations.

Transistors in computer processors often turn signals on or off. However, transistors can also change the amount of current being sent. For example, an audio amplifier may contain a series of transistors that are used to increase the signal flow. The increased signal generates an amplified sound output. Because of their low cost and high reliability, transistors have mostly replaced vacuum tubes for sound amplification purposes.

While early transistors were large enough to hold in your hand, modern transistors are so small they cannot be seen with the naked eye. In fact, CPU transistors, such as those used in Intel's Ivy Bridge processor, are separated by a distance of 22 nanometers. Considering one nanometer is one millionth of a millimeter, that is pretty small. This microscopic size allows chip manufacturers to fit hundreds of millions of transistors into a single processor.

Updated October 7, 2011 by Per C.

quizTest Your Knowledge

What statement regarding multiprocessing is false?

It can be accomplished with multiple physical processors.
It can be done using a single processor with multiple cores.
It requires more than one computer.
It is supported by both Windows and macOS.
Correct! Incorrect!     View the Multiprocessing definition.
More Quizzes →

The Tech Terms Computer Dictionary

The definition of Transistor on this page is an original definition written by the team. If you would like to reference this page or cite this definition, please use the green citation links above.

The goal of is to explain computer terminology in a way that is easy to understand. We strive for simplicity and accuracy with every definition we publish. If you have feedback about this definition or would like to suggest a new technical term, please contact us.

Sign up for the free TechTerms Newsletter

How often would you like to receive an email?

You can unsubscribe or change your frequency setting at any time using the links available in each email.

Questions? Please contact us.