When was the first microprocessor introduced?

The first microprocessor, the Intel 4004, was introduced in 1971.123

Developed by a team at Intel Corporation—which included engineers Federico Faggin, Marcian "Ted" Hoff, and Stan Mazor—the 4004 was a large-scale integrated circuit that contained the arithmetic, logic, and control circuitry necessary to function as a computer's central processing unit (CPU). While it was originally commissioned by the Japanese calculator company Busicom for use in calculators, its versatile, general-purpose design marked the beginning of the microprocessor era and the subsequent development of microcomputers.123