When it was discovered that semiconductor devices could perform the functions of vacuum tubes, integrated circuits were born. It was Geoffrey W.A. Dummer, a radar scientist, who came up with the idea of building integrated circuits for the very first time. In 1956, he made an unsuccessful attempt of building a chip. Jack Kilby of Texas Instruments and Robert Noyce of Fairchild Semiconductor co-invented the integrated circuit around the same time. Since the development of integrated circuits, they have been used in computers and cell phones.
The microprocessor is the most complex chip in a computer. A microprocessor is capable of executing millions of instructions every second. Be it a desktop or a laptop, the microprocessor is the most vital component of a computer system. Interestingly, a microprocessor is nothing but a computer chip in itself!
For something more on computer hardware, go through this list of examples of computer hardware.