A CPU is the central processing unit of a computer. It interprets and carries out the basic instructions that operate a computer. The term “CPU” is often used interchangeably with “microprocessor.” CPUs are found in computers, cell phones, digital cameras, home appliances, office equipment, and vehicles. Early CPUs were limited to a few thousand instruction sets. Today’s CPUs have billions of instruction sets and can process trillions of instructions per second.
The first electronic computer, ENIAC, used vacuum tubes for logic gates and could perform only about 5-10 operations per second. Modern CPUs use MOSFETs (metal–oxide–semiconductor field-effect transistor) or CMOS (complementary metal–oxide–semiconductor) for logic gates and can carry out millions or even billions of operations per second. They are also many orders of magnitude smaller than ENIAC; a 2018 Intel Core i9 chip measures approximately 4 cm2, while ENIAC occupied over 1,800 m2 (19,000 ft2).