American scientists John Bardeen and Walter Houser Brattain observe the basic principles of the transistor, a key element for the electronics revolution of the 20th century.

John Bardeen was an American physicist. He is the only person to be awarded the Nobel Prize in Physics twice: first in 1956 with William Shockley and Walter Houser Brattain for their invention of the transistor; and again in 1972 with Leon Cooper and John Robert Schrieffer for their microscopic theory of superconductivity, known as the BCS theory.

Walter Houser Brattain was an American solid-state physicist who shared the 1956 Nobel Prize in Physics with John Bardeen and William Shockley for their invention of the point-contact transistor. Brattain devoted much of his life to research on surface states.

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in integrated circuits. Because transistors are the key active components in practically all modern electronics, many people consider them one of the 20th century's greatest inventions.

Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other electrically charged particles. It is a subfield of physics and electrical engineering which uses active devices such as transistors, diodes, and integrated circuits to control and amplify the flow of electric current and to convert it from one form to another, such as from alternating current (AC) to direct current (DC) or from analog signals to digital signals.