First junction transistor

Today in 1951, the bipolar junction transistor was announced by its inventor, William Shockley. It was an improvement over the bipolar point-contact transistor which was invented four years earlier by John Bardeen and Walter Brattain and became the device of choice in the design of discrete and integrated circuits for the next three decades.

See PBS’s website on the history of the transistor and the website of the Transistor Museum