Yesterday we showed a picture of the Eniac, which was the first modern computer. The individual computation elements in this computer were vacuum tubes. They made the computer large, expensive, and prone to breaking down every day or so. People soon realized that the vacuum tubes could be replaced by Shockley's transistor, which was very reliable. The problem remained, however, that tens of thousands of these transistors had to be manually soldered together, and all the solder connections were prone to failure.
In 1958 Jack Kilby had a brilliant idea. Instead of building individual transistors on a piece of Silicon and then wiring them together to make a useful computer, Kilby showed that you could build ALL the transistors on a single piece of silicon at the same time. This idea became the modern integrated circuit. It got rid of both the vacuum tubes and the wires and solder.