The first microchip invented is credited jointly to Robert Noyce and Jack Kilby in 1958. Though both were working for different companies and coming at the invention from slightly different angles, the two companies decided both had part of the overall answer and decided to cross license their inventions to come up with one unified piece of technology that would revolutionize the electronics industry. The microchip, after being demonstrated in 1958, was first available commercially in 1961.
The technology was quaint, compared to today's standards. The first microchip held one transistor, three resistors and one capacitor. Today microchips commonly hold more than 125 million transistors in a space smaller than a U.S. penny.