The transistor is 65 years old today, so many happy returns to the electronic component that in contrast to the biologic species which invented it gets ever smaller with the passing years.
Without the transistor you would not be reading this on the interwebs. Nor would you have a mobile phone, a television, or much else for that matter.
What is a transistor? It is a switch and amplifier of electrical signals. With three connections, a voltage applied to one pair of terminals changes the current through another. Arrange many transistors together in an integrated circuit, and you have the basis of all electronic gadgets.
The transistor is the fundamental building block of electronics, and since its development in the late 1940s it has shrunk in size. In the latest computer processors each transistor is only around 20 billionths of a metre across. This is approaching the scale size of molecules, so the devices cannot conceivably get much smaller while continuing to obey the laws of classical physics.
Where next for electronic materials and devices?